It turns out Cosmic Eidex is a rather complicated mixture of different Jass games. It’s basically Swiss Jass, alright, but there’s something else, too. The basic structure of avoiding to be the middle player of the round comes from Mittlere or Plus-Minus. In the original version players collect sticks (good) and potatoes (bad), which cancel each other out. Cosmic Eidex is derived from Plus-Minus Jass, where the potatoes are forgotten and players strive to get seven sticks.
10 of stars, Wisdom or Weisheit, comes from Weis rule in Swiss Jass. Everybody has the option to display Weis sets, but only the best Weis scores.
Guggitaler (7 of hearts) is another Jass variant. I couldn’t find a description anywhere online, but it probably goes pretty much like in Cosmic Eidex, ie. the card points change.
Differenzler (10 of lizards) is one more Jass variant. Trying to guess the amount of tricks one makes is pretty obvious variant to any trick-taking game.
Skater (B of lizards) is one of my favourites: the card ranks in the game are Skat ranks instead of Jass ranks.
There are of course several card powers, which are clearly inspired by Cosmic Encounter: Laser and Zombie are the most obvious titles.