So how do the other iterations of English exist in their universes? After fucking with Alternia he presumably went to Hussie’s mansion and then to the furthest ring.

The same way we have Jack English. He doesn’t go to different Universes- Different Universes are infected with the Cue Ball (Scratch’s Seed) and/or Lil Cal (English’ Vessel). Doc Scratch implies having hijacked the First Guardian process of many other Universes, thus bringing LE into said Universe eventually, while the mere presence of Lil Cal (Transmitted through Nightmares), is enough to possess someone and channel English’ Soul through their bodies. So yeah. He’s born anew every time.