Precision Auction.
Club Teams - IMPs
Experienced EW but only an occasional partnership - couple of tournaments and a handful of club sessions per year as partner.
NS less experienced but more regular partnership mostly based on club sessions
Double was intended as diamonds.
The explanation given was a doubtful "I think its for the majors".
Later EW claimed that they had no agreement. This particular auction was not on their system card.
Have NS been damaged?
Personally I felt that north should have bid game. The north hand is a very powerful 19 hcp - at a different table I opened 2NT and I virtually never upgrade into a 20-22 range. So I felt that 2♣ followed by an invitational 3♠ opposite a partner who freely bid 2♠ caused the bad result rather than any affect from the misinformation.