[blml] Cheater's paradise?

[Andre Steffens]

North has:
63
765
A942
Q974
 
 
AQJ87
K
KQ7
AKJ5
 
Bidding goes (South dealer):
2C-2H
2S-3NT
 
North thought to show 3-6 points with 2H and a maximum with 3NT. So let's
assume that use of UI is absent.
 
However, South stated that NS had recently changed their system, 2H now
showing a good suit. So he did not alert the 2H bid. Their convention card
confirms this. North however keeps firm in that 2H shows points only.

East has AQxxx of hearts and now doesn't lead the suit. Result 3NT+1, while
with the lead of a small heart NS would have made 9 tricks (the king of
spades was off side).

I am not particularly interested in how to adjust, but about how to
establish if there has been an infraction:
Question 1:
Misbid or misinformation?

Question 2 :
If misbid how to deal with Law 75D2 first paragraph vs 75D2 example 2?
"After calling the Director at the earliest legal opportunity (after the
final pass, if he is to be declarer or dummy; after play ends, if he is to
be a defender), the player must inform the opponents that, IN HIS OPINION,
his partner's explanation was erroneous."
But: (in the case of misbid) "South must not correct North's explanation (or
notify the Director) immediately, and he has no responsibility to do so
subsequently"
-So: North should have called the director, failure to do so is an
infraction and we can adjust even if we rule misbid?
-Or: there was a misbid, so north did not have to call the TD,  even though
IN HER OPINION South had misexplained? No harm done: score stands?

Question3:
This situation seems to advantage both the player who doesn't know Law 75D2
and the cunning player who will state that he erred even if he knows that
partner misexplained, while the honest, knowledgeable player will cause to
find his opps the killing lead.

How do you solve this?