by Proc he means Processed Randomized Occurrence (I believe is what Proc stands for if i remember correctly... either way its used to mean "chance on hit") Edit: Upon checking his link, i guess maybe i was mistaken and it does stand for procedure, dunno where i heard the above - either way its still meant to mean chance on hit.
As for why its not working, I'm not sure. I'll play around with it in my editor and see if I can get it to work.
Edit: I just got mine working.
in Abilities > Demolish, I changed:
Data - Chance to Demolish to 50%
Data - Damage Multiplier (to buildings): 30.00
I then made a bunch of ziggurats and a tinker that could use robo-goblin at lvl 1. he did 10 dmg per hit a few times and then he did 300 damage.
I'll try it at a lower percentage, and see if for some reason it breaks.
Edit 2: Still works for me at 10% proc rate.