Having struggled with this exact issue for a syntax that is essentially an additive variant of an existing one (JavaScript), I definitely agree. Nova is halfway there to allowing this via template scopes; halfway only because this injects the extra scopes everywhere in the parent syntax, including into comments, strings etc. The other half, I think, would be a way to restrict scoping of template scopes to a context, e.g. via selectors similarly to how the context selector for completions work.