Okay, in that case I would put all the media in the complete downloads folder and import all the torrents to qbittorrent in one go. You can tell it to watch a folder for new torrent files to import.

At that point I think you can do the library import I mentioned above. Go through all the radarr settings first to make sure it imports how you want it to. You’ll probably want the hard link option at least.

Then, you’ll want to disable monitoring on the existing media, because radarr will probably be unable to identify the quality, and it’ll assume it’s the worst quality tier and re-download it (assuming you have all that configured).