This is one of those very impure situations. In fact the best we can do, or so I think, is 2H making 2 for -110. We have to hope the opponents do not play optimally to do better than the lousy 1.5 in 2H. If pard plays in 2NT undoubled, and if they lead a small heart to the stiff Jack on the board, holding the trick, then declarer can run six tricks for -100. If he tries to make it, they can make him regret it. So 2NT X is bad, if they get it right. I think 3C also goes down 2, or it can. Again they need to first double and then defend well. But the defense is easier this time.
For a 2H contract, it is best if I lead the spade J. Declarer would like to lead hearts toward his hand, but he first needs to play a top heart to drop my Jack. He also needs to lead a club toward his Kx. Dummy has KQ tight of spades, so if I start a spade and pard hops up with his ace when the club is let and plays another spade, we hold 2H to 110. Or so I think. We cannot stop declarer from getting three spades, four hearts and a club, but the job is to keep him from getting five tricks in hearts.
Here are the hands.
Let's look at 2H first. Say I start with a spade and a club is led from the board. If pard ducks, declarer lays down the ace of hearts and goes back to the board with a spade. Heart from the board. he will play me for a stiff heart on the auction. If pard plays small he takes the 9, cashes a spade, ruffs a spade which can be over ruffed but he has his three spades and a club, and he will be taking all five hearts. No better if pard splits. Go up, spade spade ruff, over ruff, hearts are good.
That's the best we can do against 2H.
Playing in NT, a low heart is led. In 2NT undoubled, now taking four diamonds and a club is a fine idea. In 3HT doubled it went club to A, small club. This could be seriously bad: spade to Q, heart through, if declarer rises then spade to K, heart through, ouch. Declarer can play small and hold it to down 3 by playing small a T3 but it doesn't matter.
So why did thins not happen? From East's viewpoint, instead of QJxx of diamonds, S could perhaps have held Kxx in spades. In which case underleadin the ace of spades would go small J Q K, spade back.
Seems to me that on the second club, W needs to plunk down the club T. Maybe E should get it right, but a little help can't hurt.
I wasn't planning on posting the full hand since I imagine everyone has a bit to regret, but there is a point: Pard has more than I can reasonably expect, and still we want to let them play it. Unless they err. Well, people do err, and it is matchpoints, so we live dangerously.
There was a 3D off 2, a 4D (???) off 1. 3C off 2. A 2NT off 1. All not doubled. I have not thought through optimal result on all of these.
Btw: In 2NT with a small heart lead, if declarer decides to settle for six tricks and runs his diamonds, he can make 7 tricks, at least if he has x-ray vision.