If you rename it using your BitTorrent client, it should still seed fine.
If you’re on Linux, a better option in my opinion, is to make a symlink to your Jellyfin folder and rename the link. The torrent client will see the original filename. Jellyfin will see the new filename.
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In my case, I’ll move the finished file to my Jellyfin library (since that’s what my backup software points to). I copy the original filename temporarily. I rename the original file how I like it. Then I make the symlink into the folder I’m seeding from. I then rename the link to match the original filename.
Too much work to delete the torrent.
Just let it seed forever.