It never really left. It got removed from the app store briefly but they reversed that decesion pretty quickly afterwards. I've also never had any issues with it on iOS so I'm curious why OP thinks it's a broken mess.
Only broken mess I'm experiencing seems to do with iOS integration of 3rd party keyboards. I think the apps are supposed to remember which keyboard you want to use with them, but the SwiftKey regularly persists even in apps in which I didn't switch to it.
I wish I didn't have to use it, but until Apple rolls out swipe and autocorrect support to my native language, I'll have to suffer.
For me SwiftKey is far superior to either native Apple keyboard or Gboard. Native keyboard has insane issues with autocorrect with multiple languages, to the point where it's not usable for me. My native (Polish) language also has fairly bad dictionaries. It's really bad overall.
Gboard is much better in that, but it has a lot of minor bugs that annoy me constantly and they refuse to fix them. Gboard will randomly show up with weird scaling issues until you hide and reopen keyboard, sometimes it will just randomly crash and restart while typing, often has layouting issues when switching orientation. Google clearly just doesn't care enough to support it.
SwiftKey fixed most of those annoyances for me. I dropped it when they said they won't support it anymore but I'm actually happy they reversed that decision and I just installed it again.
