I use Picard, I never had a issue of it changing the actual file, just adding mp3 tags and cover images. I didn’t even know it could mess with the length of the song, maybe check your settings? Most issues I’ve had with Picard have been connection issues, but that usually gets fixed with clicking the refresh thingy.

Anyway, I spent like a week doing 4-8 hours of “work” per day to get my existing music library tags and filenames sorted with Picard. Since then, all new music that gets added to the PC is put into a temp folder, ran through Picard and only then moved into the music library folder.

For the file tags I use the defaults that Picard comes with, I also have a plugin that adds additional musician information into the song. Picard also changes the directory and filenames into /Artist Name/Album Year - Album Name/01. Title.flac, so for example /Björk/1993 - Debut/01. Human Behaviour.flac

Recently I started adding lyrics as .lrc files, but that looks like its going to be more work than its worth. If I wanted all songs to have lyrics files, I’d have to go through most of my non-English language songs manually, the apps seem to have some issues with that. Also, for stuff like Kent, who have 2 albums in Swedish and English, the apps don’t seem to understand that and insist on using the English lyrics for the Swedish versions.