No, it’s not specifically in the rules. It’s just implied by the fact that the damaged area is on the back side of the card, away from the main sea zone area. This is more pronounced on the Japanese card than on the American one. Do you think this needs to be added to the FAQ? This is the first time it’s ever come up.
A specific update for this is probably not necessary but as part of a bigger FAQ update it probably wouldn’t hurt.