Interesting take on code gen. We went the way of declarative -> text/template (Go vs jinja in python), but use CUE as the input. Here, we can do many of the things that you implement in the translations and hybrid method.
We actually used to do something similar, but were able to remove tons of code and move that to the user layer so they can control, because each language has its own patterns and snowflakes. Basically lift the DSLs, transforms, and templates out of the implementation. CUE also provides some really powerful building blocks for schemas, aggregations, and defaults, while also reducing how much we have to write as humans.
https://github.com/hofstadter-io/hof
