AI confuses City Cede with City Return

[Tiramisu]

I am playing with mods, but I am definitely sure that this bug is created by Firaxis: So in peace treaties the AI sometimes thinks that it is better for them to give an occupied city away to their enemy than getting it back. That is why you can demand the Cede proposal much easier than the "Return to owner" proposal.
In fact a Cede demand actually allows you to get even more demands in the peace treaty. However, sometimes the AI gets it right, but I dont know when or why.

Unfortunately I have found no entry in the XML to fix this bug. So Firaxis needs to fix this asap!