I use jellyfin a lot for anime, no plugins. I just label all my folders like kaguya_sama_[tmdbid-12345]
.
As long as the The Movie DB id is there, aboslutely no problems indexing.
I’d like to add that Jellyfin has a provider order that it checks for metadata from. I had some issues until I changed the order to pull metadata from the same provider that Sonarr and Radarr use. Once it checked there for metadata first, everything lined up and I’ve had exceptionally few issues.
What provider is that? I have just of my metadata issues resolved but occasionally I find a season all messed up.