Earlier quoted context omitted.
Have you considered adding LLM features for the negotiations? Could be cool.
You are getting downvoted, but this is a cool idea. Diplomacy has historically been a weak part of the series, and being able to shore that up may be a lot of fun to play against.
This experience led Soren Johnson (co-designer of Civ III and lead designer of Civ IV) to the realization that Civ AIs are supposed to "play to lose" [1].