installed elog 2.5.5 agin, same effekt with "back" / "zurück". checked the 
language file eloglang.german witch seem ok for me and the translations are 
well done. removed then in eloglang.germen the traslation for back and checked 
this: still back was viewed. reinserted the translation "Zurück" (just this 
word!)and checked again: everithing looks fine, no longer back, correctly 
Zurück on the button.
absolutly no idea why and whats the difference was! bus it works...
thank's stefan!  :-)

> > 2. the "back" link is clear and tranlated to "Liste". But I mean the back 
> > button 
> > in the entry and the edit mode (see picture)...  ;-)
> 
> Well, if you try with the demo logbook, the "Back" button is translated
> correctly, so I don't know whats wong in your case. Can you check that your
> eloglang.german file is intact?