OK I found a couple of bugs...
+Version 1.0
+Multi-board:
-The Multi-board lags out sometimes. It is opened and blocks the screen and you can't close it. That happened in chapter 3.
-Its calculations aren't always correct:
--In chapter 4 it said: 'Mini-bosses killed: 5/4'.
--In chapter 5 there are 8 mini-bosses. When I killed them all, it said 6/10 mini-bosses killed instead of 8/8.
--In chapter 6 I did all the optional quests, the epic and the elite quests but the multi-board said: Optional quests done 1/6!
--In chapter 7 it says optional quests done 3/9, although I've done them all.
--In chapter 8 it says: Steal 12/15 although there are only 9 steal-able items in that chapter.
--In chapter 10 it says: Optional quests done 2/0.
--The attack-speed calculations are a bit off. Sometimes it's 7.012 for Fradz and other times it's 0.112 for Phodom!
--The Multi-board shows the critical chance and critical damage, but I've never seen the characters throughout the whole campaign do a single critical, unless it's hidden unlike the Blade-master's critical... Or like the criticals of the Omega Set.
+Galeoth:
-Galeoth's 'Magic Hammer' skill creates a permanent visibility modifier. You can always see the area wherever you cast that spell even if you're not there anymore.
-If/when Galeoth dies in a chapter, when he revives, his line of sight is greatly reduced.
+Music Tracks:
-At any given time, except the start up of the chapter, there are two music tracks playing 1 and 8. A main music track and another one in the background.
-During the Chapter 3 Epic Boss fight, the played music is the same as the Elite Boss fight.
+Spell book spell upgrades:
-They're inverted. The upgrades do the opposite of what they're supposed to do. For example the 'Quick heal' upgrade for Phodom's first spell book spell does what the 'Strong heal' upgrade should do and vice versa. Same with Fradz's Spiral Shield.
+Items:
-Some aspects of some items don't work properly. For example:
--The Myth item 'Aero' stacks to no end. In other words the STAT bonus has no limit. At one point the item gave me at least 110 bonus to all stats (During a long fight in chapter 8) while the maximum bonus should be 15 (at least it says so in the description).
--The Ring of Tides in chapter 3 (lucky box) doesn't add armor or magic damage.
--The Illusion created by 'Mask of Illusion' (chapter 3 lucky box) isn't identical to the hero as it takes a lot more damage.
--Phodom's set doesn't create a shock-wave.
--The mummies created by 'Life Stealer' don't gain 10% hp and attack for every 50 stats of the hero. I tested it by adding more stats to the hero (alchemy, super holgro, three paths, blessing of lightning). It seems that the maximum hp is 3000 which contradicts with the item description.
--The armor bonus of Soldier's Set 3 is zero at maximum charges.
--Orb of Degeneration/ Rune Cloak/ Galeoth's set: I'm not sure if they actually stop the enemies' regeneration. It doesn't work on bosses anyways. Might need more testing.
--Same with Cloak of Fire/ Phodom's Set. No fire aoe effect there.
--Magic Orb 6/10 adds 10 intellect.
--Magic Orb 7/10 adds 20 intellect.
--Magic Orb 8/10 adds 30 intellect.
--Magic Orb 9/10 adds 40 intellect.
--Ultimate Orb 10/10 adds 50 intellect. Seriously it's not in the description. It also adds 2200 magic damage instead of 1200.
--Eternal Set gives 12 armor, but the description says 10.
--Adamantine Guard doesn't have enough description. (No quality, no background story).
--Not all items with aura effect work from boxes. (Outer Stone works, Zocmo's set doesn't... and the list goes on.)
--Omega Set, the best item set of all, can be sold in shops for 500 gold.
--Boxes can't be used to combine Zyl Orbs or Magic Orbs, but in chapter 10 they can.
--Demon Sphere loses its slow poison effect in chapter 10.
+Swap bug:
-The "Swap" option in the boxes only works in chapter 4. I tried it in other chapters and weirdly it removed the items from the game, instead of switching between the inventories.
-Even when it works, it removes the charges on chargeable items (Starting items (sword of haste, aegis shield, etc...)).
+Bosses:
-Sometimes during some boss fights, boss spells don't do anything. In other words, the bosses just become invulnerable for a while and apply the channel animation but do nothing. For example the epic bosses of chapters 1, 3 and 6.
-During chapter 7 Epic boss fight against Siluze, one of his spells has some death bolts appear around the arena then they get stuck on the sides. And they don't disappear when the quest ends. They're also attack-able and spells can be cast on them which makes their damage dealing null. Same with the fire balls that Xirenze (Chapter 9 elite boss) fires.
-Chapter 2 Epic Boss has very little mana. I was able to burn all his 300 mana early on (Magic Torment combat king) and he couldn't use any spells the whole fight (On Extreme difficulty).
-Chapter 5 Epic Boss phase 2 (2nd level John) casts a spell that only targets upwards (It should target the heroes but it targets up instead. 90 degrees.).
+Child Pictures:
-Dalli guards.
-Tauren Totem in chapter 2 barbarian village. (Why is there a Tauren Totem anyways?)
-Pack Horses in chapter 4.
-The three dragon slayers in chapter 4.
-Dragon Spirit (Epic Boss of chapter 4).
-Villagers, female villagers, children and Road Guards in chapter 5.
-Vampire Mages in Kar'Gath.
-Lord of Kar'Gath.
-Dragon Searcher and some sellers and citizens in Chapter 7.
-Kaddammn (Master Treasure Hunter) in chapter 7.
-Cannon Tower in chapter 7.
-Shadow Demons (The Mystery Portal quest) chapter 7.
-Terdoom Castle Guards. (One of the guards near the southern gate doesn't have a floating text when you click on him).
-Zhitenxa (Epic Boss of chapter 8).
+Heroic Achievements:
-You do get the bonus/ reward when you achieve them, but they are neither saved in the multiboard nor in the panel (they're saved in the chapter you get each one in, but the next chapter they're gone).
+Chapter 5:
-At the beginning of the chapter the heroes have less damage than before; in other words for example Phodom had 146-226 damage in chapter 4, and in chapter 5 he had 124-125. Same with Fradz.
EDIT: It was a self-correcting problem probably... because when they leveled up their damage went back to normal.
-The Turtle mini-boss stays invulnerable and doesn't cross to the other side of the river if you cast Flash Strike on it. (I know what the reply to that one should be:'Well, how about you don't do that?' lol)
-The teleports are bugged. Sometimes when I use them to teleport Phodom, they teleport Fradz instead. Other times they do nothing at all. Also, you can use them even if you don't give the magic ball to the mage (on condition that you finish all the other quests). I even saw that bug in a play-through on YouTube v1.8c.
-After delivering the letter to Billy, all portrait animations of characters disappear. That takes as long as 3 minutes before they comes back. Not a major bug though...
+Chapter 6:
-After the Elite Boss fight with Faerga, the fire beasts re-spawn on the walls of Kar'Gath. You can see them from the inside next to the 'Black Merchant' on the wall.
-After the Epic Boss fight with Jurxy, all music stops.
-Executioners stop patrolling after the first Boss Fight (Xada).
-Uummut doesn't disappear after the Xada Boss Fight. Not sure if he's meant to though...
+Chapter 7:
-If you summon your boxes in the arena to switch an item or so, then you get out of the arena, you cannot summon them back again.
-The final arena fight with
The Elementalist has an issue. He has a spell where he teleports behind the character, sometimes he teleports outside the arena and gets stuck in the wall. This goes on for a while until he teleports again which is conditional.
-The 9 circle puzzle where you try to make them all the same color by stepping on them, it's very buggy. There's a chance when you step on one circle that another circle appears next to it. By the time I had finished the first locker there were over 15 circles on top of each other!
-Sometimes the auction hall bugs out. Sometimes the auction master declares an item 'sold' even before the bidding starts. Other times one of the other characters in the auction hall bids when the auction master says sold, so the auction hall is bugged and I neither get the item I was bidding for, nor get to see the rest of the items. Other times there's a sale on two items at the same time....
-Difficulty buff doesn't apply on arena contestants.
+Chapter 8:
-The riddle questions are bugged. Sometimes the questions are outdated asking about the vitality (which was removed), other times it asks about weird characters like Lavareon (who the heck is that?), and sometimes I answer the question right and it says wrong anyways!
-After finishing chapter 8 you get 15 extra lives for no reason. Thanks BTW

-This is a frequently mentioned bug: Gaomdo disappears and doesn't come back, but this is untrue. He always comes back it just takes time. The maximum is 2 minutes.
+Chapter 9:
-The game crashed when Keeper of Vengeance cast a certain spell (the one where he burns the heroes' mana).
-The effect shown around Fradz when fighting off Axobada's mind control sticks till the end of the map.
-Sometimes the game crashes when fighting Jurxy, during the Yurgimar fight.
-Riddle questions are bugged like chapter 8.
-The 'Special Font' used in all the other chapters is not applied in this chapter.
-During the Elite Boss fight (Xirenze), sometimes he casts his Breathe Fire ability during the short cinematic where the death knights view the fight, that doesn't give me a chance to dodge that ability or heal.
+Chapter 10:
-In the second phase of Zylcious fight, one of the death knights (the one that looks like a night elf warden) teleported to where Zylcious was standing (that small cliff) and I couldn't get to her so I had nothing to do but fight Uummut... which ended horribly for me.
-The 'Library' puzzle, after finishing it the path doesn't clear up so you have to elaborately use the 'Teleport stone' to get out of the library.
-Magic orb + Zyl orb (In one inventory) = both disappear?! Seriously?

-Magic orb 9/10 + Zyl orb 1/6 = Ultimate orb 10/10..... Why? The 10th Magic orb is in the library anyways... what's the point?
-The teleport to the library is bugged. When you access it, even if you press no, it teleports you to the library anyways.
-The bonus luck from the Lucky Horseshoe/Lucky Clover... etc is added to the total luck in the multi-board even if they're not in the heroes' inventory.
-Golems (Defenders) don't have the game difficulty buff, even when you attack them and they become hostile.
-The Cinematic where the heroes ask the popags about the 'Mystery Box', the one that contains the zhyon, is shown even if I've already solved it and beat the zhyon.
+Interludes:
-Chapter 2 and 3 interludes cannot be seen. The game says 7500 game points needed or 10,000 game points needed, but I have 14k+.
++NON-BUGS:
+You said that a player shouldn't be able to 'grind' in this campaign, but does it include farming? Because there are many areas in the campaign where you can farm charges for your items and experience for your heroes in many chapters; like chapter 2 Noc'toriah Mausoleum, chapter 3 first puzzle of Epic Boss area, chapter 4 during Elite Boss fight, chapter 5 during Epic Boss fight, chapter 6 Forgotten ones quest and Immortals puzzle, chapter 7 the quest given by the archbishop and chapter 8 the quest called 'The Challenge'.
++If I may suggest:
-Maybe a minor alteration in the luck system? Maybe it would be better if it was by choice? I mean if you have maximum luck you should be able to choose the item you get instead of just getting the best item. For example in chapter 9 instead of getting Oelivert if you have 30+ luck you get to choose which item you get (from the items of the luck box).
-Making minigames random? For example the Kar'Gath teleport and Nightmare minigames have a certain pattern, you only have to go through them once, and then you can memorize the pattern and finish them in a minute in the next play-through, unless they're randomly generated, and that would make them fun in every play-through.