Edit: OP actually has a simple folder structure, and transmission-create works fine, so no need for anything more than just looping over 1st level folders and files with a simple shell script.

Basically you’d want to map seasons to folders within the torrent files. I found the torf python library on github that looks good, but there are two questions:

• what’s the structure of those XML files, what do they contain?
• seeing the mass of torrents you want to create, it wouldn’t hurt to cache the cryptographic sum of the files’ blocks for the chosen block size, unless this is already in those XML files

Not that I’m implicitly saying I’d write a program to do this (I’m very unreliable), but looks like you’d need to go the programming route (you or someone else). It’s a matter of walking your folders, finding those XML files, parsing them with a library (python has a built in one), finding what to do with that info exactly, and passing it to torf. And preferably, saving the cryptographic sums, as well as the progress of the program. If you have the cryptographic sums in the XML files, it’d be worth it to make the program concurrent with threads, as it would be about reading and writing files as fast as possible, and this could be so fast saving progress would be pointless.