You can test the id tags by just playing one song from the disc and seeing if it come's up labeled correctly. Just double click it. I'm not positive on a Mac, but I know on a PC id Tags are carried with the song file, they are not cataloged on a seperate file. If it plays in the player with the proper tag, then the issue is not your burn.
It sounds like a DB error to me, probably created when she imported the songs to the library. Look for an odd character or slash in the name of one of the songs or bands.
My portable Napster player is not able to play Stellastarr** because of the "*" in the bands name, although the media player in the Napster Desktop can play it fine. It turns out the DB that runs the Napster player uses Boolean for some categorizing and the "*" represents an unknown character. It screws the Stellastarr** folder up and few of the playlists that have Stellastar on them.
When I removed the "*" from the name, no more problems.
So look for a !,*,/,\,%,& and see if it might be the culprit that screws up the DB. Songs like 1% by Jane's Addiction and bands like !!! and +/- are all well known culprits.