I do tagging as a final step before release, rather than using Reapers tagging at render time or the Media Explorer tagger. This allows me to ensure that all rendered files are tagged the same way at the same time, whether bwf, wav, flac or mp3 (etc.), in a single window.
It also saves a lot of time, since tagging only happens once, and only on files the client has approved for release.
I use this one:
https://kid3.kde.org/
If you want to verify the tags after, VLC or foobar2000 is very good. But I've found Kid3 is pretty bulletproof, fast and easy, and so I no longer need to use another app to verify the tags.