Syntactical feasibility/implementation advice

Per discussion on this issue, kicking off a separate one to ask advice on syntax feasibility and implementation strategies.

I started exploring a DST for javascript along the lines of kotlin builders, JFX and JSX. I've only written some high level ideas and started kicking off a sweet.js macro implementation prototype.

Can you help me sanity check (a) whether the syntax here is feasible or not (i.e. does it create ambiguity with the JS grammar (you can make comments here directly if you'd like)? and if so, what are the most common strategies to avoid them) and (b) once we settle on a feasible design what's the best way to go about it wrt sweet.js?