I'm just not convinced that something like CoffeeScript would benefit technically from compilation to a different target than JS. When the purpose of a language is simply to have all the features of another language, but with nicer syntax, what is to be gained from rebuilding all of those features from scratch?
The one quasi-counterexample I can think of in that subset of languages is Objective-C which essentially just adds sugar on top of C and can be transformed relatively simply to C (there are library functions you can use to build classes and objects and call methods from scratch, using no actual Objective-C syntax). My understanding is that Objective-C compilers don't go through C as an intermediate, but this is merely to reduce compiling time, not to improve efficiency at runtime. If Objective-C did target C instead, the end result would be identical.
The one quasi-counterexample I can think of in that subset of languages is Objective-C which essentially just adds sugar on top of C and can be transformed relatively simply to C (there are library functions you can use to build classes and objects and call methods from scratch, using no actual Objective-C syntax). My understanding is that Objective-C compilers don't go through C as an intermediate, but this is merely to reduce compiling time, not to improve efficiency at runtime. If Objective-C did target C instead, the end result would be identical.