Would you be interested in evaluating (or having your LLMs check out) my geometry kernel Aetheris for your project? I already have DSL (called Firmament) parser/lexer/AST part down, and it is designed to be easy to extend, so you don't have to write everything from scratch.

https://github.com/yuechen-li-dev/Aetheris

One of my goals when I built the kernel is I want to make building a pro grade CAD software as easy as wrapping a web frontend around the Aetheris libraries. It's still very much an aspirational goal though.