One of the devs here. We plan to release an updated code generator (jolie2java) that will make it easy to do exactly that. (For Java, but Jolie is already designed to support other langs as well in the future.)
Specifically, you'll be able to use Jolie to write (tech-agnostic) APIs and then implement them in Java, using types automatically generated from the Jolie APIs.
This is good to hear - the big problem I have with justifying more niche languages is that I have to ultimately use some niche library at some point that only exists for more established languages.
I hope you guys try to make a first class transpiled language.