Yep, that's another one! I investigated the issue today and discovered that we had based our implementation on a bad localization table. Both were taken from MSDN, go figure. Anyhow, I've updated the languages table on the wiki:
http://wiki.opengarden.org/Deki_Wiki/Languages
The correct resources name will be 'resources.de-de.txt', but since the wrong table was encoded 'Names.php', that won't work. Luckily, the workaround happens to also be the right way to do it. Save your localization file as 'resources.de.txt', which is a the neutral German resources file. This file should _not_ be selectable, but it is due to a bug. Now, create empty files with the region-specific names: resources.de-at.txt, resources.de-de.txt, resources.de-li.txt, resources.de-lu.txt, and resources.de-ch.txt.
Finally, select the 'German (Austria)' file from the Control Panel. While this is technically not the right locale, all German speaking countries fortunately use officially Hochdeutsch, so the locale doesn't make a difference (although, having a Switzerdütsch version would be hilarious! (no offense to the Swiss!

)).
I'll check in the corrections to Control Panel tomorrow.