Of those you mentioned the only ones I have never seen spawn without my intervention are Romania, York and Lancaster. I beleive they are leftover tags from EU3 where they could spawn, but never played that game.
Nizhnyi Novgorod and Zadoblahblah spawns more rarely than the others. I actually quite often see Aquielia and Tirol spawn as a result of war between Austria and Venice, depending on who wins. Styria only ever spawns when Austria seriously screws up several times during a playthrough or as a result of rebellion.
Bashkria happens now and then, they can spawn from both Kazan, Nogai and Uzbek I beleive.
Nizhnyi Novgorod and Zadoblahblah spawns more rarely than the others. I actually quite often see Aquielia and Tirol spawn as a result of war between Austria and Venice, depending on who wins. Styria only ever spawns when Austria seriously screws up several times during a playthrough or as a result of rebellion.
Bashkria happens now and then, they can spawn from both Kazan, Nogai and Uzbek I beleive.