ai_soldier.lua should be in your scriptbank.
It uses the ai/module_combatcore.lua 'module' so in the top of that script you will find all the animations and sounds listed.
I'll look into the soundset stuff and see if I can figure out if it still works.
Ok, so the soundset system does work:
The attached script simply plays a random soundset entry when you approach and resets when you walk away.
Demonstrates in as simple a way as I can think of how soundsets work.
By default GG loads the 'soldier' soundset, I'm not sure why Lee stopped using this system in the ai modules but it shouldn't be too hard to put it back in.
Been there, done that, got all the T-Shirts!