Author here! When CoffeeScript 2 got released about 6 years ago, me and a few others went all into it, because huge effort went into supporting ES6 features in the compiler.

Still, TypeScript appeared 1 year after and took over everything.

I had to use both heavily, and I am 3x slower and more verbose in TS than CS. But hobby dev is not what guides adoption.

It's what gets used inside companies that decides this, and companies prefer slow but stricter languages, that help devs collaborate. Not languages that allow super fast development but results into hard to revisit code.