There are some spelling and grammatical errors in the german translation. For example in the preferences:
wrong: Zeige offline-Freundesliste an
correct: Zeige Offline-Freundesliste an
original: Show offline friends on list
Maybe the more correct translation would be: Zeige Offline-Freunde in Liste an.
I know, it looks like a small difference, but “off-Line” would look like a small different too. But it hurts eyes.
Another example (Observer games tab):
wrong: Korrespondenz Spiele
correct: Korrespondenz-Spiele or Korrespondenzspiele
original: correspondence games
In German, word parts are written together or at least hyphenated (the linguistic technical term is durchgekoppeln). Spaces are incorrect, result in a different stress and, in the worst case, in a different meaning.