First page under symbol jump states that it is based on and can be extended using .sublime-syntax format. At this point of time I was expecting language server protocol support.
LSP support is planned! Although, the rationale for including it is for advanced language features, like "go to method". I'd be surprised if other editors were using it for syntax highlighting. I've had to jump through hoops to keep that performant on large files. Seems like putting that in a separate process would make performance even more of a challenge.
I found this after a quick search: https://github.com/Microsoft/language-server-protocol/issues...