The problem at this point is not the sheeting but the ventilation.

If the crawlspace is open to the basement at any place, you actually should have no vents open to the outside.

Or if the crawlspace is not open to the basement, the vents should remain closed in summer when surface temperatures in the cool crawlspace can allow warmer outside air to condense.

Your issues now aren’t related to the insulation or sheeting. They are related to the ventilation.