Where are you getting this information that there is NO open adult-only area? I just got off the Sun Princess and there are TWO adult only areas on the ship. The Sanctuary and The Dome are currently AO. Not only that, but the Sanctuary was a literal ghost town with barely anyone in the area even on sea days. I had access to the Sanctuary, but couldn't really use it as I was traveling with a minor, so I was quite upset that the Dome area was also made AO as that pushed most families to the Lido Deck for pool access.
As for Park 19, yes, we asked and they are still awaiting the safety certification as has been posted.