I've noticed that when I tag files using Musicbrainz, the recording ID doesn't seem to get populated, which is required to have Picard and other tagging tools find the right album release, in order to do more complete tagging. Otherwise it has to just do a fuzzy match based on either tags or acoustid, both of which might find the wrong version or multiple different albums rather than the one it should. The key to doing a non-fuzzy lookup in Musicbrainz is to have the tags save the musicbrainz_recordingid, which for mp3's is the UFID:http://musicbrainz.org tag, and for flac/vorbis/opus/apev2 is MUSICBRAINZ_TRACKID. abcde doesn't seem to populate this, so doing further tagging is often frustrating and unreliable, or just plain wrong. https://picard-docs.musicbrainz.org/en/appendices/tag_mapping.html#id21 https://musicbrainz.org/doc/MusicBrainz_Identifier
This is using version 2.9.3. I forgot to add that on the initial report, and I don't see a way to add it now.
I believe this exists because abcde uses MusicBrainz for lookup purposes only. It uses it to populate CDDB-compatible data. This also means that anything specific to MusicBrainz gets discarded (developers: please correct me if I'm wrong). I'd still welcome such a feature. CDDB data is often of poor quality, while MusicBrainz data is of much better quality; but often the case is, there are many releases (or sometimes even totally different CDs) with the same discid. As a minimum having the releaseID tagged to the files would hugely reduce workflow for any further tagging; conversely not having the releaseID tagged in means the user needs to identify their CD twice; first when ripping with abcde and later (if tagging by abcde is determined to be not sufficient for any reason) when improving tagging with, say, MusicBrainz picard.