Not really, it would be tedious, but idiomatic coffeescript can be converted to idiomatic javascript basically on a line-for-line basis. Also the compiler really does produce readable code (though unmistakeably computer-generated), so the process might even be sped by reducing it to just tidying up compiler output.

It's a task that could easily be spread across any number of human translators, too.

The main limiting factor is the quality of the test suite, which dictates how quickly typos could be found.