I don't own the game from the Adventure Shop, so I can't help first hand (I'm no official word), but do you think there may have been an installer option that you overlooked to select the language? Or perhaps there's a way to change the language in-game? The French for settings is "paramètres", is that available from the menu?
The Adventure Shop may have accidentally hosted the French files on their server, but I'd imagine most languages would come under one installer so that seems unlikely. Either way, the language on the
game page is listed as English, so don't worry, you didn't buy the French version by mistake.
