I actually mentioned this on the last stream with Rudy, but despite .ogg and .opus audio files being generally very compressed, while retaining good audio quality, I don't know of any simple command line tools for tagging them. If anyone does, keep me posted about them! I've tried most of the stuff in the Arch repos and the AUR, and I can't find something that doesn't require some GUI that loads the required library, or requires you to tag while encoding.
As I think Rudy said, ncmpcpp doesn't have the ability to tag these files either, and I suppose some other library is either required or unintigrated into it.
I've put this on the Hacking Wishlist, but hopefully the solution is something simple and obvious.