My point was that you could implement type checking with macros, not that you could type check macros. (Though that would be cool!) As opposed to having to change the language definition first (Python) or implement an entirely new compiler (TypeScript).

Certainly you can implement the typechecker with macros, but it should also work on macros, before expansion. That is, you likely want (-> ...) typechecked as written, not (only) as expanded, and typing errors reported on the non-expanded form.