Yes, you can use the Linear Extrusion filter to convert your line surface to a polygon surface, and at that point ParaView can compute normals on it. I was going to suggest this first, but you said you want to integrate some value based on this, so I wasn’t sure if changing the mesh structure is going to affect whatever this integration operation you are planning on doing.
I’m not sure why you are worried about traversing the cells in the order of the airfoil’s wall. An integration (on a discrete mesh like this) generally means you are summing something up, and the order you sum things up does not matter. The direction the normals point should be consistent unless there is something weird with your input mesh. I think it would be a safe assumption that the order would be correct.