I'm not a specialist, but, AFAIK, the engine itself is limited to 2020 provinces. There's no walkaround. And so you have, as an example, MyMap for FTG if you want 2020 provinces. If you want 10.000 provinces, ok, ask Paradox for a new engine and a new game. I don't see any means FTG team could have released something like that with their licenced engine. Anyway, it will be much easier to handle with a 3D engine able to rotate and zoom, as even with 2020 provinces, I know there are people complaining that some provinces are too tiny.