Sorry, I'm late on this one. As the rule is written, it doesn't matter that the ball was in the penalty area. I don't know the area in question, but if the players thought it was possible that the ball could be lost but still in the non-penalty area, the provisional is allowed. I'm picturing a scenario where you're not sure whether or not the ball actually made it into the pond, you're allowed to hit the provisional as long as you announce it.
That q-school story though, that sounds like a major screw job. Even if they all saw the splash, I think you could still put up a reasonable argument that it's possible the ball skipped or ricocheted off a rock back beyond the stakes.