I just hope OP posts an update if he made it 3 days or not

My python script works pretty well if I do say so myself but I'm pretty biased lol. It matches things up pretty well since it will use filenames of the actual media content or the different ids that it gets fro IMDb or whatever other providers you have available. The filenames should work pretty consistently assuming you are running Plex and jellyfin on the exact same library and the IDs should work if you are keeping different servers with different files in sync.

I like to run Plex for my homies and Jellyfin for myself. I even made a python script that will keep my user in sync between Plex and jellyfin in the event that I use Plex by accident, also runs in a container. I also run Fileflows which let's me do any type of processing on files, in my case I use it for videos to encode my remuxes to h265 via av1an so I can target a vmaf value instead of a filesize or crf and I have that run on 4 different servers in parallel.