Lightroom: Shift + X no longer does Reject And Next (German)
You can work around this problem by editing the file "TranslatedStrings_Lr_de_DE.txt" and changing this line:
See this article for how to edit TranslatedStrings. That article mentions TranslatedStrings.txt (used in earlier versions), but now you'll have to edit TranslatedStrings_Lr_de_DE.txt.
There is a similar problem with the shortcut X for Reject in French (whereas Reject and Next worked in French).