Have the players been influenced by their own side's alerts or explanations?
Problem 3: Unauthorised information

Alerts and explanations are for the opponents' benefit - not for that of the alerting side. A player who makes a bid which he thinks is natural is not permitted to base his subsequent bidding on the fact that partner has alerted, whichever partner has made the mistake. If the agreement is that the bid is natural, the bidder is not allowed to know that partner has misinterpreted it; if the agreement is that the bid is conventional, the bidder is not permitted to allow the alert to wake him up to the fact that he has himself forgotten the system.

If S in case 1 believed that 2 was natural, then he has a huge ethical problem when he hears his partner alert it and bid 2. The ethical situation is that the 2 bidder must assume that his partner has made a natural 2 response to a 2 weakness take-out, and he must bid accordingly. That suggests that opener has good Hearts and no liking for Diamonds , so if responder has good tolerance for Hearts along with his Diamond suit, he has a responsibility to pass (or raise) 2 rather than simply rebidding 3 and hoping partner gets the message.

Similar considerations apply in case 3 if East overcalls 2, thinking it is natural, and W alerts and responds 2. In fact there is much more scope for W having a natural 2 response in this situation - after all he could have 6+ Spades and a void Diamond . E is not allowed to bid on the basis that W is only supporting a Spade suit W thinks E has shown. Instead, he must assume that W has a Spade suit of his own. A 3 rebid would only be acceptable if E has long Diamonds and very short Spades.

It is quite possible for problem 2 and problem 3 to occur at the same time.