This is weird, the strings are only translated in english, none of the other languages are working.
I'm just stuck.

I got it. Somehow the translation files for tinymce's advanced theme (tinymce, the themes and the plugins have separate files). I guess that happened when I made the slim lined zenphoto tinymce theme for the admin edit pages. Somehow they were moved instead of copied... You can download them on the tinymce website if you need them right now and place them there. But I will readd them soon.

Update: I just updated TinyMCE itself and readded the missing languages. Everything should be back to normal now...

I've updated to the last nightly (zenphoto version 1.2.3 [3498]).
Everything is fixed.

THANK YOU !

You are welcome..:-)