I can't say for sure but I believe one of the reason is the first review in the world for Perp was on a French website (http://www.mondespersistants.com/articl … test-:953/ sorry there is no English translation) followed by a fansite and a forum there. Meaning many French players heard about the game. I'm not sure if there is the same for other communities like the German one.
Japanese anime and culture are quite popular in France as well and I suppose the idea of driving a Mecha is maybe more appealing to this community.
If you check in Eve Online for example the German / Russian community is much bigger than the French one and it was the case already before they had the translation in their own language.
In the future these communities will most likely catch up with the French one if Perp follow the same evolution.
Where we go one, we go all.