The main issue I have with tree-sitter is that it’s approach can’t work for many languages I care about: Common Lisp cannot be parsed without a full lisp implementation; Haskell’s syntax is complicated enough that the grammar is incomplete; C/C++ can’t be parsed accurately if only because of the pre-processor; parsing perl is Turing-complete, etc. I think the suggestion elsewhere makes sense: don’t make us write parsers in a new ecosystem, but instead define a format for existing parsers to produce as a side-output.