Yes, you're correct, it's the decimal separator. I remember now that this is not international. I believe the comma is used in the US? Having grown up in France, I'm used to the dot.

And that score is indeed suspicious, although there are some protections to prevent cheating. Someone would have to be quite motivated to go around them. But it might be possible, as you don't need to flag all the mines in order to win, you can wind by just uncovering the non-mines. I felt this could be allowed as this is really the same outcome. But I can see that if you're really lucky, the mines are placed in a very convenient way, a quick win could happen. But I assume this can only happen on the beginner grid, not on the larger ones.

In any case, I'll reconsider this, and may force all mines to be flagged in order to win, that might be safer.