Currently in edit previews and edits themselves, it only displays the artist credit so you don't really know from a diff if a link has been changed. This is causing immense confusion to users, as noted in
MBS-2378, MBS-2476 and many edits and releases being added to the DB with incorrect (or stale, after changing the artist credit text) linked artists, but correct artist credits.
Take http://musicbrainz.org/edit/14590656 for example - a casual user can't be expected to hover on the links to see that the MBIDs are different. This causes users to think that MB is entering bad data, when it's actually a mixture of a non-intuitive UI and some bugs (currently).
How about making the artist credit more obvious, and displaying Artist In MusicBrainz in the edits and previews?
So for that edit above:
Release Group: Deep Space by Audio Hijack
Artist Credit: Audio Hijack -> Audio Hijack
Artist in MusicBrainz: Audio -> Audio Hijack
This would be a bit harder for display in Edit Medium or Add Medium, but I really think we need to make this functionality more obvious to users.