Like 99% of all AI problems of this game is solely caused by simultaneous turn. I am not sure whether this is possible at this point, but reverting the game back to one-by-one turn would immensely help AI to actually function. I believe this solution will also work on Sorcerer King as well.
Oh, this will also probably allow us to use auto-save. The core reason why auo-save file is corrupted is because the engine attempts to save stuffs when simultaneous turn is in process. one-by-one turn would at least minimize data corruption or hopefully eliminate all.
Yes, turn time would increase a lot, but it's still better to have AI to actually semi-function instead of barely function.