Back in 2011 we built yatta solutions as a startup around template based roundtrip engineering. UML lab would use templates to not only generate the source code from UML diagrams but also to 'parse' the code.

I don't know the current state of https://www.uml-lab.com/en/uml-lab/ because I left for other adventures, but if you are looking for a tool that can actually keep code and UML in sync give it a try.