I've used some other fonts, because I don't have the fonts installed which you used

Download here:
hxxp:auf-dem-olymp.de/Files/xpbuttonstranslated_german.zip
[nonactive]To install, just copy in a new folder called "german" in your Themes\XPTheme\images\ folder
in german:
Um dieses Set an deutschen Buttons für das XPTheme zu installieren, einfach neuen Ordner "german" unter Themes\XPTheme\images anlegen und dort reinkopieren!
I hope you like it