It appears that they did. It was called LunaScript.
We did long ago, but ditched that idea because we get to use the tools of JS and we realised that effectively using a DSL embedded in another language allows the developer to break the rules of the DSL.
Surely those points apply to TypeScript.
Lunascript was very different from JavaScript, partly because it had automatic support for our reactivity system. As a result it compiled to JavaScript that looked nothing like the original code (even the control flow was different). Reading this code was very difficult.
The IDE support for TypeScript is actually pretty great; building our own tooling support for LunaScript felt like something we didn't really want to have to do.