It's all automated for each one, and yeah they write the metadata into the folder. I have Radarr/Sonarr/Prowlarr + Ombi + rtorrent, which pretty much automates everything. I just type in what I want and it shows up in all 3 a minute or two later. Sonarr also keeps track of TV schedules, so if it's a new show that is still airing it automatically shows up when a torrent of it becomes available.
I actually run Plex, Emby, and Jellyfin. I would like to only run Jellyfin, but unfortunately some devices will not have jellyfin, but will have plex and/or emby. The main reason I personally still use Plex (or sometimes Emby) even though I am running Jellyfin with all the exact same stuff -- is because Jellyfin sucks at live TV / iptv. It's interface is complete trash and I can't seem to get a good "guide" going like I can with Plex or Emby. If that can be resolved then I'd definitely only ever use Jellyfin.
Interesting, I'm surprised they don't hit you with automated copyright claims or something. I wonder if you can use youtube-dl to help 'extricate' your library? I've used it to auto-convert my music playlists into mp3 files, and it's always worked great.
You can use youtube-dl-gui to grab mp3's from many different platforms.
I also grab mp3's using ymusic and a hacked pandora app on my phone. I miss the days of what, waffle, and oink though. Still haven't gotten into orpheus yet.