This debate is borne of an apples to oranges comparision.

First lets consider the "screened" wing. The screen will have some small resistance to air passing through it as mentioned before, but given enough flow some of the air would follow the airfoil shape. This would give you the classic differential pressure between the top and bottom, but because it's a screen the air would try to flow through the wing from bottom to top. Again, given enough air and enough differential you could probably get some lift out of it, but it would be very inefficient. So it might work, but not well.

In the case of your glider, you retained the covering on the first 1/3 of the wing. This is really the most critical part. So the wing was still able to generate some lift. I can't imagine it was too efficient, but luckily for you it behaived all right and you were able to save the model. However, I doubt you'd win any endurance contests with it.