[DaveBlake]

The compilation "Armageddon: The Album" has a track with
artist = "Journey feat. Steve Auger"
It should also have
Musicbrainz artist id = abd506e1-6f2b-4d6f-b937-92c267f6f88b; 24e6290c-8e4d-469f-9f89-0527118ef659
the values for Journey and Steve in order.

Just to point out that the Musicbrainz database is wrong here as Steve's name is actually Augeri !! www.steveaugeri.com

Steve is listed correctly on Musicbrainz and his MBID is af30ff69-6232-41c8-b3f8-73e20165625d - It is just that one track that is incorrectly identified.

Troy would have that album in his collection

I wonder if the MB entry has been edited recently? That could explain how Troy has the mbid in the wrong order, yet Picard now returns it the in the correct one. Not withstanding that it is a mythical artist!

So yes there are mistakes in the MB database. It is based on collective knowledge, so the only thing to do when such an error is found is correct it on behalf of the MB using community. By using mbids, the contribution Kodi can make is to widen that MB community - more people looking at the results of tagging with Picard (or any other Musicbrainz enabled tool) and able to feedback corrections to Musicbrainz.