So, you have TS already, but played with the idea of rewriting it in CLJS? I think the idiom of all Clojure is, stick with what works; Clojure has always placed a high value on being pragmatic.
I don’t know much about Fulcro, but I would be tempted to at least get the syntax benefits of Reagent (Hiccup) in an attempted re-write. I could be mistaken, but my understanding is that the opinionated nature of Fulcro is unlikely to co-exist peacefully with a re-write of TypeScript (which is also somewhat opinionated, by nature).
As I’ve heard said on many other “Clojure vs Other” answers, you can’t just rewrite their code and their strategies in Clojure and hope in improve; Clojure invites different ways of solving some of the problems.
The interop, though, is a different thing. Sometimes you can’t and shouldn’t bypass all of that – it would be reinventing the wheel. But from your example I again wonder if Fulcro adds a layer of complexity to interop?
I find my mind keeps drifting back to the discussion at Dynamic types: where is the discussion?