Is the EXIF tag XPKeywords (used by e.g. Windows 7 for tags) imported by Lightroom as keywords? If not, is there some more indirect way to import the data?
A quick search says that yes, the XPKeywords field is imported as Keywords: https://forums.adobe.com/thread/772784.
That said, it's worth noting that the many "XP..." fields are not standard EXIF fields so I would not expect them to work.