You are importing foreign assumptions that obscure the plain meaning of Scripture. It was literal water that fell from above. The opening of the windows allowed that to happen. If the water is literal, the windows are literal. Case closed.
I hate to say it depends, but it does. Think of (American) football officials spotting the forward progress of a ball carrier. Suppose the running back comes down around midfield, and the official spots the ball at the 49-and-a-half. Was the official right or wrong? Almost certainly, his decision is good enough. If he spots the ball at the 41 yard line, he is certainly wrong. Where is the boundary between right and wrong? What if he spots the ball at the 49? Probably OK. How about the 48-and-a-half? Probably wrong, but maybe defensible. How about the 47? Almost certainly wrong. And the 40 yard line would be indefensible.
As in football officiating, so in paleontology. There is no bright, numerical line between what can be accounted for by evolution and what cannot. But there are some things like Precambrian rabbit, or a Jurassic primate, that would be paradigm-shaking. They would be the equivalent of spotting the ball at the 40 when the runner was tackled at midfield.
So do you have any examples of Precambrian rabbits or Jurassic primates to offer?
EDIT: Fixed grammatical mistake.