LOL hahahahahaha. I was so preoccupied with writing the script, I just wrote some random placeholder text for the event popups. I'll put a little bit more effort into that now haha.
No, they'll sap on a random segment of the wall. Makes logical sense that the sappers will do their thing on the weakest section of the wall they'll find, but makes no sense for the general to deploy away from the breach -_-
Yes, I created a separate script for the AI. As they can't make yes/no decisions like a player might, the AI gets a small chance to breach the walls each turn they besiege a sapping-enabled settlement. This will work on both human- and AI-controlled settlements.