First of all, I'm an absolute Linux and especially Linux Mint Newbie, so I hope I catched the right area for the bug I found (and corrected myself).
It's concerning the "locale LC_MONETARY" where the Value for "mon_thousands_sep" in de_AT is WRONG! I found this bug, when I installed GnuCash and was suprised that there was a Space instead a Point as Thounsands-Separator. ... Then I looked it up, what the Austrian standardization institute says about, and it says there has to be a Point.
So I corrected the de_AT File in this point and newly installed it in the system. Now it's working fine.
Info: I'm using Linux Mint 13 "Maya" with MATE and presettings for Austria/German.
I would suggest the developer's to correct this in the Installation-Files for all other users as well!
I hope I'll able to help reporting bug's in future too.