blackshoe, on 2016-March-31, 22:16, said:
Let me ask you. Dummy ask declarer if he has any spades. Declarer says no. Are you going to call the director if you're dummy? A defender? Declarer? I submit that none of the players at the table should call the director unless either a defender is reasonably sure declarer did in fact revoke, or declarer later realizes he was mistaken, and he did revoke. In the latter case, if the revoke has not been established, he should correct it immediately, and if it has been established, he might as well wait until after the play, since nothing can really be done about it until then anyway.
It was an incident of this sort that caused me to generate the OP, which is derived from it. What happened was that declarer revoked at trick 2 by ruffing (a club with a heart trump) and when asked by dummy said that she had no clubs when in fact she still held one. She then played on. This was the second board of a 3-board round, and the defenders only recognised that they had been misled when they discussed the hand after playing the third board. Yes, they could have realised at the end of the second hand if they had been fully on the ball, but it had ended with declarer claiming by saying "I have only trumps left"; the defenders hadn't counted declarer's trumps sufficiently accurately to realise that she must still have held one plain card, and accepted the claim.
The question is then how the TD adjusts the result. If attention has been drawn to the revoke by the question and answer, then neither 64B4 nor 64B5 apply, and rectification is under 64A; otherwise (the defenders have called to the third board) it is under 64C.
Hence my earlier remark, which you appear to be echoing: "This is where the problem lies - the defenders may well not [call the TD], because they do not realise that there has nevertheless actually been a revoke."
For completeness, I'll note that the scenarios of the OP of course apply mutatis mutandis to revokes / enquiries by a defending side.