This summarises what should have happened ( taken from Taradale bridge club website on correct protocol):

Wrong Explanation of a Bid •

If your partner has explained your bid incorrectly, don’t call Director. You are not allowed to take notice of his/her mistaken explanation to change your bidding. You must continue to bid according to your system/ agreements.

• If your partner realises his/her explanation was mistaken during the auction, s/he must immediately call Director and correct the explanation.

• If your side becomes Declarer, call Director and tell the opp about the mistaken explanation before they lead.

• If your side becomes Defenders, notify Director at end of game

So EW were arguably not disadvantaged by North's correct alert of 2H as per their agreements. South should however have called the director as soon as they remembered the correct explanation for the 2D opening bid after the alert of 2H. If South had called the Director they would likely have allowed the auction to proceed with the instruction that North was to ignore any unauthorised information.

If South failed to call the Director North should have called the Director before the opening lead after the auction. Without a correction, the leader may have made a suboptimum lead based on the incorrect information opener had diamonds.

Hope this is helpful. 

thanks sean, very succinct explaination.