In the current version of Sexskripts the umlauts are not displayed by the German translation properly.
Recht hast du!
I just noticed the same, but can't really explain, why that's the programm. I think, that the english language package doesn't contains this "Umlaute".
If it doesn't work just replace "ö" with "oe", "ä" with "ae" and "ü" with "ue".
This is an alternitave kind of writing the letters in an slightly older way.
No problem, SexScripts is in Java, hense in utf8, every characters are usable. It was only a manipulation mistake from myself, corrected in the next release.