If you read the top of the fandom page you link, you will see: "Three episodes from this season ("Open Book", "Story for Steven" and "Shirt Club") were aired during Season 2. ". Consequently, taking in account that we list the episodes in the order of their broadcast, these episodes should be listed as part of the 2nd season.

Your answer on the airing order is correct, however the correct viewing order places them in season 1, as that is the intended viewing order. Placing them in season 2 results in continuity errors.

See here from the creator: https://ianjq.tumblr.com/post/123939657564/now-that-all-the-season-1-episodes-are-out-could

It is also explained in this thread: https://www.reddit.com/r/stevenuniverse/s/gjHy5DesmE

The main episodes list should always follow the original airing order.

You have an episode group available for the intended order.

Sorry, I'm new to this site so I don't fully understand, what do you mean when you say "You have an episode group available for the intended order."?

If the context makes any difference, I'm running a jellyfin server that is pulling metadata from here, but is labelling the episodes incorrectly as I have them stored in the correct watch order. So far I've had to manually rename and edit descriptions, so if there's a better fix I would be very grateful.

I mean this.

With Kodi, you use them this way.

I can't help you for Jellyfin as I don't use it.

Thank you! I believe the is a way to use NFO with jellyfin, I will check it out and should hopefully fix the problem!