Awkward. Perhaps for Anno Domini, I'll need it to be a governor only then?It is a conflict between Scipio and CP. I enabled Scipio and CP, tested the Proconsul City Founding, and got the crash.
By the way, what I meant by "All I've changed is the cost/strength of the UU" was exactly what it says - i.e. I've not gone meddling with any of your code !