And it's the exact reason I'm really reluctant to fully buy into Typescript... I always feel like I'm wrong about the "not an official spec" part of things but you are 100% correct in my understanding.

Also on "it's whatever each release wants it to be" - that is hell on earth if you're looking to target consistent software processes and it only gets worse the more you scale (both solution and team).

I get the value of Typescript - hell I've used it extensively myself... it's just that I can't stop feeling like this is all an anti-pattern: trying to make a loosely-typed language a typed language (if you can call it that?). =/