Unfortunately, that's not something we have any control over, or any real guidance on. Per my other comment in this thread, Tim and I don't use TS or Flow ourselves, and we haven't directly maintained the typedefs.
I like types (I've use both Flow and Typescript) in general, but I can also admit that they can cause more type specific coding that is unrelated to the actual problem that I want to solve. It's somewhat of a rabbit hole though, it is hard to go back once you've started. It would therefore be great if there was something more than the test cases provided at flow-typed when trying to to learn redux typing.