Niceproblem! I was also surprised that my lazy / crude line worked but the bidding struck me.
After 4sf is Xed, I wouldnt bet that 2s is a 4-cd support, I would tend to think 3 and no stopper of c, and no other good call, and could still be invitational only (eg. what do you do with Kxx AQxxx Qx xxx or a jack more). So I would have bid 3s clearly forcing (or 4 if I am pessimistic but I liked my hand lol).
Also, the opener with 2 stiff honors in responders suit never sghows his tolerance (since he denied support by passing the X he cant really be any better) and bids 2nt with a dubious stopper.