When I go into the Units tab in the Editor ,I am still allowed to select between 31 different Civs. I think that must be changed at least.
A 50-turns-testplay of me has brought up no error. Sadly that is saying nothing...
I can not start the PTW part of the game. So I have to testplay it with Conquest. But Conquest has 31 Civs build in ,so no error occured ,of course.
(btw: I was able to talk with all Civs in my game.)