Oh my god, i am so sorry... i thought the german language file would translate the dashboard infos into german...
But it translated the frontend infos which where englsh in german.
Yes everything on the page, like in the footer or the Comments are german now. And i tried so often to chnage this in the css und php files.
This was my big mistake. Sorry for that

But i think its a good hint for other users... maybe they have the same error in reasoning.