Default user settings are kept in /etc/skel. When a user is created the users's /home directory & settings are copied from /etc/skel. And obviously since Klaus Knopper is German, the defaults are German.
In theory, if you delete or rename the /etc/skel/.kde directory, then create a new user & login as that user, the KDE personalizer should be run at first start.
I hope this helps.
James