My understanding was that all of the kickstarter boxed copies are english (correct me if I'm wrong, I just pledged for a digital version). In my book that's totally ok because it would be extremly costly to produce a special kickstarter box in every possible language and sort out what person gets what language.
Most likely the collectors edition and regular boxed versions sold in france are completly localized (meaning everything in french).
But as I said, these versions differ from what you got (at least the box does).
You can of course play the game in french and there might even be the translated manual on steam (not sure though).
