In re-frame you would dispatch a event to tell your application you need some data to be fetched. Once the data has been fetched (or received an error), it dispatches another event. So basically with re-frame applications, it's all events.

Also, I think the whole "callbacks vs async/await (promises)" is only relevant in JS, where callback-hell is easier to end up with. Mostly because clojure as a language (lisps really [I think?]) prefers very small, composable functions. So by just following that, you avoid callback-hell.

I'm also working on a clojurescript codebase in my daily work. Using clojure.spec to specify behaviour and simulate data for my reagent components. Transducers I have not have the need to use yet.

Regarding React Hooks, when using reagent together with re-frame, you basically end up with all components being state-less, and having the react hooks would just couple functionality to one component, so it's not really needed.