Sorry, I'm not clear on what you did... you say you "imported" the library from the internal disk to an SD card. Did you move the database to that SD card?
Why did you try doing something with the XML file?
It sounds like the reason you're having issues with relocation is you double-imported the songs unnecessarily. I'd suggest you sort by date added, remove all the newly imported songs, then use the mass-relocation tool to find the correct location of those other songs.