I believe that 99% of the time, a reuse of older technologies results in greater innovation that is more stable and a return is multiple of the underlying foundations.

This applies here as well. Typescript could go a long way.

But admittedly, writing a grammar, parser and then a whole compiler along with its tooling of a new DSL is fun for sure but does look good on CV as well.

I didn't say anything more than that.

I downvoted both of your comments because I think it's rude and insulting to assume the motivation of someone's work is self-aggrandizing, and to dismiss out of hand the work might be motivated by technical needs because you can't immediately recognize those needs. I find the attitude frustrating, similar to the other common HN dismissal of "I could build it in a weekend".