Back in my day, writing compilers was part of systems programming.
Yeah, the term has changed meaning several times. Early on, "systems programmer" meant basically what we call a "developer" now (by opposition to a programmer or a researcher).
At that time, what would have been the distinction between "programmer" and "developer"?
I hope you really mean for "userspace tools / programs" which is what these dev-tools are, and not in the area of device drivers, since that is where "systems programming" is more relevant.
I don't know why one would choose JS or TS for "systems programming", but I'm assuming you're talking about user-space programs.
But really, those who know the difference between a compiled language and a VM-based language know the obvious fundamental performance limitations of developer tools written in VM-based languages like JS or TS and would avoid them as they are not designed for this use case.