> This is exactly why simple, concise writing is essential, and their wall of text is...not it.

I only skimmed this but felt it was clear. They're asking for TypeScript, as part of the type erasure, to emit the type information it has discovered about the types in a side channel to the emitted JavaScript. Think of, say, PDB files as an analogy.

> They are really asking for a net new product which has very little to do with the TypeScript that exists today.

This is information TypeScript already has today but which it discards. It wouldn't take a "net new product".