I would recommend you look into Saltbox, which seems to align with what you are looking to do and should take considerable heavy lifting off your plate.
The solution to the rclone issues you discuss is to use a union mount, and cloudplow or similar to automatically shift files to the long term storage location, while Jellyfin will continue to see content files spread around servers in one mount location.
[HELP] Setting up a Jellyfin server with different (remote) storage servers (files.catbox.moe) angielski
Hello, not so long ago I discovered Jellyfin, and by extension Radarr, Sonarr, Bazarr, Jackett, etc....