For language-specific rules and hard-coded paths, there should be appropriate conditional blocks defined with a Windows Language = <value> rule (just as there might be for a Processor Architecture rule when the registry keys differ on x86 and x64).
The presumption in all of the above advice is that the package has been coded as English Only.
Of course, if one is using the PROGRAM_FILES common path value, then it probably resolves to 'C:\Programme' on German-language systems. -)
If one is trying to get to the equivalent of "Program Files (x86)" on a non-English system, then those adjustments should be made in the "Set Path" value also.