Hi,
I can now edit the language file from within the admin and save it, also the file gets written in UTF-8. For some reason, only the translation for "Gallery Menu" doesn't show up correct in the Frontend then.
As example for german, i translate "Gallery Menu" to "Galerie Menà¼". But only "Galerie Men" is shown in the frontend. All other words seem to work normally and are displayed correct.
Side Note: if you create a language file with the admin and use capital letters, in my example "German", the file is created as "German.xml" not as "german.xml" so upper/lowcase MATTERS. If you type this wrong in one of the theme config's for example the gallery stops working. Maybe you guys should stay with lowercase only, to prevent beginners making that failure