Hi,
we also use commas here, but I always just put in dots and never give it much thought.
It seems like a localization issue. The desktop release seems to disregard user preference and force English locale.
I didn't find any way to fix it (I'm using a game-making tool that basically exports the game for me, giving me no options). There could be a way, but this kind of issue is of pretty low priority. I'm sorry, but you'll have to bear with dots on the desktop for now.