Yesterday, I reinstalled my parents' PCLOS with a ḰDE Mini 2011.09, leaving /home untouched.
After running addlocale I realized that neither Firefox nor Thunderbird were in German language. In Thunderbird, enabling German localization and restarting changed the language, in Firefox I had to change "general.useragent.locale" to "de" again in "about:config". Enabling the German language package didn't help.
Looks like a pattern to me now.
The other laptop, where I don't have this prob is a german remaster of 2010 from pclinuxosusers.de, which does just fine.
Could this be an issue with addlocale? Would I have to delete any personalization folder (like .kde4)?
Not a show stopper, but somehow puzzling...
EDIT: just found that Thunderbird also keeps "general.useragent.locale" as "en-US", changed to "de", now "inbox" etc. are finally german, too....