Language-wise, theres nothing stopping you from parsing java, and producing equivalent semantics. There's nothing stopping you from producing equivalent jvm bytecode.
The interesting part of racket/perl6/this project is that this compilation step is being done without having to parsing "another language", by using macros. Parsing is still done ofc, but it could also be said that you're really just parsing the rust language, which happens to look like java, and producing rust code. The macro system itself is operating as the compiler, and since macros are "rust", then whats the difference?