but metadata tagging

Not possible to keep seeding changed data. Changing the file contents changes the file hash / torrent hash. There is no way to keep seeding a torrent that expects different file data.

Not sure if it's worth it but if you really wanted to keep seeding the original data then you'd need to keep a "torrent" copy of that data for qBittorrent and your own copy of the files elsewhere that you can tag and change as much as you like.

and renaming fucks the files up.

Similar solution to above, you could keep separate folders if you wanted.

But technically as long as you never change the file data (e.g. no metadata tagging) then you could keep two separate folders and have the data hardlinked between them. That way you can rename one version of them as much as you like while keeping the original filenames in the other folder.

e.g. simple example

c:\qbittorrent\torrentdata\musicstuff <-- all files/subfolders hardlinked --> c:\mymusic\blahblah

Alternatively you could do what the other commenter mentioned & rename the files within qBittorrent itself. Personally I prefer the hardlink method since that keeps the torrent client with the same expected file names it looks for, makes it easier to do things like re-install / re-seed the torrent client, switch torrent clients, etc.