Tips on software to (mass) edit mp3 metadata?

Musicbrainz Picard if you like graphical interfaces.

Beets if you like the command line.

https://www.mp3tag.de/en/ could be useful if your files are already uniformly named and if you're on Windows

If you just want correct metadata (no own adjustments), then getting it from the MusicBrainz database is probably easiest. You can use MusicBrainz Picard for that: https://picard.musicbrainz.org

It does also seem to have a scripting API. No idea how well that works, though.

Ive used easytag in the past.

There's also KID3 and Foobar2000.

I became obsessive with beets. It uses MusicBrainz IDs to sort all of the files. https://beets.io/

I do it in Winamp, but you probably just want a dedicated software like the other commenters proposed