Dynamically changing civs is quite impossible unless you change the way those json files are interpreted. This is a lot of work that could lead to engine changes. I am not sure if a single mod can achieve these things. But you can start by grepping which js files or cpp files are doing the interpretation of the civ jsons.
Yeah, he especially has "connection issues" when losing.
I don't need your invite to call your lies. Maybe it's hard to recognize but I'm not discussing anything with you.