http://bugs.winehq.org/show_bug.cgi?id=32651
--- Comment #3 from Dmitry Timoshkov dmitry@baikal.ru 2013-01-05 07:49:52 CST --- (In reply to comment #2)
Does it work better with de_DE.UTF-8?
If it did, that would be a bug, too, since the differences between two UTF-8 locales shouldn't affect this kind of thing at all. But it doesn't.
There is no such a thing as UTF-8 locale for a Windows application. If a win32 app or one of its components doesn't use unicode internally that makes a difference. Probably you should try to use de_DE.UTF-8 locale for the whole life-time of your brand new ~/.wine prefix.