To argue one of the points, I don’t really mind the huge nested “CoreAdminContext”. It’s something that will exist at a single place in the application, so it’s no big deal. The real problem with Contexts might be the usual one with dynamic scopes: determining the actual dependencies of a component becomes harder.
I spent a few years primarily as a React developer, then stepped away for a few years. A lot has changed in the time since. I find the combination of functional components, hooks, and contexts makes things much less “readable,” if that makes sense.
I think the proper react lingo would be “it’s harder to reason about” :D