I am of two minds about this. On the first hand, this is both very neat and very impressive. On the other hand, intl-proxy scares me, because it brings back (somewhat limited) JS FFI and thus a lot of the concerns around Kernel code.
I have also dabbled in Elm-generating-Elm, and believe that whatever hacks you want to use during that are fine, because at the end of the process you either have valid Elm code or you don’t. However, I see in the examples that some use cases require the use of intl-proxy in the application that uses the generated code. Would you consider moving to a pure-Elm solution for locale-aware formatting if one was available?
Blatant plug: I started on such a pure-elm library, although it is not feature-rich enough yet to cover this use case: elm-cldr 1.0.0