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We play mixed cues.
(eta 3♥ description cut off: since S's 3D showed a card, it looks a lot like a slam-seeking bid, in which case 3♥ makes sense as a cue. But a 4-3 ♥ fit could be our best game, so perhaps opener's 3♥ should be patterning, showing 3 cards in the suit?)
I'm not sure there's any blame here since there's not much room for anyone to have bid differently, but S said the undisclosed Q♠ made the slam playable - without it (eg with Q♥ instead), on a ♠ lead, he struggled to see how he'd pitch the S loser given N's missing KC. Even with it, slam looked a long way from laydown N didn't disagree, felt he'd made a bunch of systemic bids describing his hand, which S also agreed with, with the conceivable exception of 3H. So - blame? Bad luck?