Thank you for posting a your review!
With regards to the adult-only areas of the ship, enforcement is an ongoing issue virtually all lines that we've cruised. Sometimes crew steps in but often they do not... kind of the same issue as with saving deck chairs :/
There may also be language in the contract that specifies under 18 may be allowed to use the adult pool in certain circumstances... but that's a contract-specific issue so read your agreements carefully if it is that important an issue to you. Happy cruising!