"You pilot always through an unknown future. Facts are your only clue. Get the facts!" - Robert A. Heinlein,
From the Notebooks of Lazarus Long
I have looked at all the WBFLC minutes I could find (those from 1997-2004 are available online). There is no minute that says anything about "acceptable" deviations in high card strength or length.
Unless East tells you, in response to your question, that he
deliberately bid 1NT on 18 HCP, knowing their agreement was 13-15, you can't call the bid a psyche (a psyche is a deliberate action). Note also that a psyche is a "gross distortion". This hand fits, IMO, but if he didn't do it deliberately, it's still not a psyche.
Law 75 requires the TD to assume MI instead of misbid "in the absence of evidence to the contrary". The only way to obtain such evidence is to (a) examine the putative offending side's convention card(s) and (
ask them questions (for example, ask East why he bid 1NT with 18 HCP when their agreement is supposedly 13-15, ask West if East makes o habit of this misbid). If they are unable or unwilling to answer questions, then the only evidence of misbid is the CC and the fact that the bid was explained as 13-15. West bid 3
♣, and then passed East's unusual 3
♥, so I don't see any evidence of MI in West's actions. Seems to me the 3
♥ bid is evidence of misbid (but why didn't he just bid 3NT in that case?) All things considered, I'm inclined to rule misbid rather than misexplanation, but...
Even if you rule MI, the damage to NS was caused, not by the MI, but by North's off the wall (IMO) 3
♠ bid. So IMO there is no case for a score adjustment. However, if the TD decides there is such a case, it would be to an assigned score, not an artificial score. You can't give an artificial score adjustment when a result has been obtained at the table. Well, you can in certain cases, if the SOs regulations allow it, as the EBU does, but I don't think that applies here.
EW appear to be unwilling, but not unable, to talk to the TD about this hand. In f2f bridge, that would rate a PP or a DP, but my understanding of the situation at BBO is that the software does not allow those options. If that's the case, I would lobby for a change in the software. If that's not the case, I would give this pair a PP (how much depends on the conditions of contest, really - in the ACBL the 'default' PP is 25% of a top; other places it's 10%).
If the TD decides that EW have a concealed partnership understanding (CPU) - in this case if there were evidence (from West's answers to the questions he won't/can't answer
) that he was aware East might have the stronger hand he actually had for his 1NT bid - well, there is no explicit provision in the laws to adjust the score. The laws simply say that CPUs are prohibited. Thus, if you decide they have one, issue a PP (possibly a warning, for a first offense), and tell them they must in future give correct explanations of both their explicit agreeement and their implicit one. You
could use Law 12A1 ("The Director may award an assigned adjusted score when he judges that these Laws do not provide indemnity to the non-offending contestant for the particular type of violation of law committed by an opponent.") to adjust in this case, but you still have to judge that the NOS were damaged by the CPU, and not by their own poor* bidding.
*Poor bidding, per se, is not a cause to deny redress. The action must be considerably worse than just "bad bridge". Some SOs use the phrase "wild, irrational, or gambling" here, some don't. This is an area where a poll of the player's peers might be helpful.
If you decide to adjust, you use Law 12C2 to decide what the adjustment should be. That is an exercise I will leave to the reader.