Yep, this looks pretty good to me.

BTW, I noticed that casouri mentioned the idea of a "primary" parser here. Sorry, no direct link -- please search for "primary parser".

Is that somehow different from the "main" parser mentioned here?

BTW, I noticed that casouri mentioned the idea of a "primary" parser here. Sorry, no direct link -- please search for "primary parser".

Is that somehow different from the "main" parser mentioned here?

Yes, from the Emacs documentation:

Generally when there are multiple languages at play, there is a
"primary", or "host" language. The parser for this language--the
“primary parser”, parses the entire buffer. Parsers for other languages
are "embedded" or "guest" parsers, which only work on part of the
buffer. The parse tree of the primary parser is usually used to
determine the ranges in which the embedded parsers operate.

I wrote "main or host", it could also be "primary or host".