I got a bit confused while looking at these triggers. From what I saw, I can tell that you aren't doing things right in more than 1 way(s). So I guess I'll just tell you how your triggers should look like:
Event: a unit spawns a summoned unit:
set temp_int = (load integer 0 of summoning unit from the table) + 1
save unit (summoned unit as temp_int of summoning unit into the table)
save integer (temp_int as 0 of summoning unit into the table)
......................
Event: a unit begins channeling an ability
...
Actions:
set temp_int = LoadInteger( 0 of triggering unit from the table)
loop ~int~ from 1 to temp_int
Order Load Unit ( ~int~ of triggering unit form the table) to attack-move to ....
This way you basically keep the '0' of the table to count how many skeletons has this unit summoned. the '1' field contains the 1-st skeleton, '2' contains the 2-nd, and so on..
The loop is from 1 to 'the amount of skeletons' - it picks each skeleton and orders it to attack-move.
Ofc you will also need to save the summoner into the skeleton's table too, and when a skeleton dies - you run a loop to reduce and re-set the skeletons in the caster's table, but I think you should be able to manage that
ALTERNATIVELY (this may be kind a easier)
you can save a unit GROUP handle into the caster's table, and when it summons a skeleton:
load the unit group, and add the skeleton to it.
when you start casting the spell - load the group again, and use it as a normal unit group.
you also need to save the unit group handle into the skeletons' tables as well, and when they die - load the unit group, remove the skeleton from it, and clear the skeleton's child hashtable.