I have a similar question : for TSTW mod, we would like to have different kinds of 'governements', to allow each faction to deal with conquered provinces in different ways.
For Successors' factions, I'd like to have 3 kind of 'governements' :
Colonisation (only hellenistic units and buildings)
Rule the city with a leader from your faction (access to some hellenistic and native units, hellenistic buildings)
Let the native rule their land (only native units, access to some native buildings)

How would I make that in a way the AI can handle it ? I've seen a few mods in which the AI never built added buildings.