I would actually complain about this and if it was not communicated to you at all during your booking, I'd expect some kind of compensation. Unless there is a sister property you can use.
WOW. Glad it worked out in the end and you were able to look on the bright side. So sorry for your friends.
It is super frustrating that the water park was closed, though. I would have been really mad b/c my kids would have been incredibly excited to use the pool and just crushed when it was closed.