What a cool project, would be interested to hear how it works for folks IRL.
I think it would be a mistake to go in and expect (or demand) a perfectly polished experience. That they even managed to retrofit a multiplayer mode onto a strictly single player game is a completely mind-blowing achievement in my book - esp. given how well it works, all things considered.
This version "Reborn" is a complete rewrite of "Skyrim Together" which was available then shortly abandoned back in 2019/2020.
The team here has done a mind-blowing job, and this release in particular is extremely stable for what turning a singleplayer game into a multiplayer game is!