Basically, normals tells the renderer which side is the inside, and which side is the outside.

Poser 4 didn't really care. It rendered both sides the same. But Firefly doesn't like reversed normals. The Angelyna Wings are really old, and were probably made before P5. I think they were modelled inside out, only no one cared until Firefly came along.

To reverse the normals, use the grouping tool. You will have to do it for each existing group. Select a group, click "reverse normals," then select the next group and repeat until you've done all the groups. Test it by rendering; you'll probably see if you've missed any groups. Save the wings to your library, and you'll never have to do it again. They'll take the same textures and poses as the original wings.