option nodeadkeys is "Akzenttasten or Akzent-Tasten" not Akzenttatsen
Can you provide more information as to where this message can be found? I didn't find it in xfce4-xkb-plugin, I also looked inside xfce4-settings but nothing in view.
After a look at the xkb-translation and grepping through the Xfce repository checkout, I haven't found anything as well.
But now I found out that this wrong translation is more deeper in the system -- same wrong translation appears when running console-setup which I incidentally just ran on another PC aside of me.
You can try to track the translation down to whatever component is really having this string mistyped. In any case, please close this bug.