I don’t think geography is the best metric to divide revolutions. For one, there aren’t revolutionary nations in most of these places. Revolutionary countries are also far more linked to their mother countries. Location in the game requires a good amount of suspension of disbelief anyways.
If you wanted to restrict or mix up what revolutions are available, I’d make it contingent on choosing certain cards or politicians (kind of like how you get the tank as Italy). I think it could be fun to actually have a secret revolution.