Intriguingly Familiar Start
Argentina reached a nice slam using an auction that looks familiar to me.
Opener Palazzo held Axxx-AKxx-K-KJ10x and opened 1C.
Responder Lambardi held Kx-J10-xxxx-AQxxx and responded 2C.
So far, fairly normal stuff. However, things got interesting, as Opener's next call was 2D! Those who use Golady, however, will find this auction fairly normal. Responder showed any GF hand with no 5-card major OR invitational with clubs (check). Opener then bid one under his cheapest four-card major, hearts. I'm not sure what Argentina was playing, here, but it happens to be identical to how I would bid this thing.
LHO decided to intervene by doubling the diamond call. Nothing like advertising the value of the opponent's stiff, eh? So, Responder clarified his hand with a 3C invitational call.
Opener, undoubtedly sensing from the friendly double that 3NT was a bad idea AND that the stiff might be quite useful for a club contract, next bid 3D. Maybe this was a cuebid, or maybe this was asking for stopper help for 3NT. Either way, Responder has a clear 3S call. He lacks the diamond stop, but he does have a spade control.
South's next call of 6C seems a bit premature, but maybe Opener predicted a problem in their techniques. I see one also, frankly. 4H might be construed as not the bid of an "out of focus major," as the rejection of 3NT might suggest a Moysian 4H. If 4S is the clear RKCB call, an answer of 4NT or 5C (1430 or regular) will not allow a Queen-ask anyway. So, perhaps Opener trusted Responder to not cooperate with a 3S cuebid unless he held good trumps, which makes a lot of sense.
South could continue cuebidding, instead. After 3S, Opener could bypass 4C to show poor top trumps. 4D sounds like LTTC, which might make sense, but perhaps that would be misconstrued as a true cue (first-round control) if the heart ambiguity problem is not resolved.
In retrospect, I think that 6C is the practical call. Responder should also have been on a wavelength of this sort and should have realized the possible ambiguity problems himself. The 3S cue sounds like more than simply a spade control. As a limited, invitational-only hand, this is a whopper. (Note the "empathetic splinter" nature of the hand, as well.)
Well done, Argentina.