I'm posting this here in case someone finds it useful or wants to contribute.
I've written a command line tool named
https://codeberg.org/DidierMalenfant/TraktorBuddy
to edit/tag/fix Traktor collections. The readme can explain more as to what it can do.
More importantly, this is also a pure Python module which means it can easily be used to write scripts that automate collection workflows or any kind of tedious tasks.
This is currently in a "works fine on my machine" state but I welcome offers to help test it (keep backups!) some more. I'm on macOS but it shouldn't be that hard to make it work on Windows too (PR submissions are welcome!).