Thanks. What I didn't understand at first and want to clarify for future visitors:
The keys in the InfoPlist.strings files must match the key and not the value from the Info.plist file. That is why you can just set the default (english) value in the Info.plist file and localize it for other languages. In that case there is no need for an english InfoPlist.strings file. I found that if you also have an english InfoPlist.strings file, the value in Info.plist is never used.