atleast with Nes's system its just AddUnitBonus(unit, bonus amount) which is about as GUI friendly as Nes is going to get. I don't know of another system besides Bonus (nes) and ItemPower (bpower, alot worsely done than Nes's, alot less GUI friendly as i am aware)
,
[Out of curiosity, does Lua or
ObjectMerger still work for you? LUA
and ObjectMerger haven't worked in a while, I'm starting to think of making my generation scripts in wurst