My view is that Java's checked exceptions failed in big part because Java didn't have type variables back then; after all, polymorphic Result types are not that much different from checked exceptions.

I haven't written any Java since it has gained those, so I suspect there might be other aspects making it awkward. And it still would lack exhaustiveness checking that e.g. Rust has.

Checked exceptions were actually the "right way" to do exceptions (if there is such a thing), the problem was just that developers hated them, but I think that draws the wrong conclusion. That tells me their syntax/usage was seen as too much forced boiler plate making code unwieldy, not that they didn't have benefits for correctness (something often not appreciated until years later).

Unchecked exceptions lead to unhandled exceptions at runtime. We've all seen screens with Java programs running with tons of exceptions in the log, or worse, that crash with unhandled exceptions. This is the result of the unchecked exceptions mess, which is why I won't use languages that use them for routine error handling for anything more than trivial programs.