I started but didn't finish a Rygel + local-search (nee Tracker) plugin to try to finally get that. I wish the upnp media services were better. I keep telling myself I'll build a nice client/controller... Some day.
One example I can point to is Stargate SG-1. Episode 1 is a two parter and depending on who you ask it's either Episode 1 and 2 or Episode 1 which causes all subsequent episode numbers to be thrown off by 1 depending on how you count.
This confusion is further complicated by the release order on DVD/Bluray, the order of airing, and the fact that all of these things can be different in different regions of the world.
And that's just one show.
I do agree that both systems are wrong. At least Plex's is more compatible with the even-more-wrong conventions of the high seas
Maybe the way I organized my library intuitively sort of matched Jellyfin's expectations?