I see three sweeps, with three rails. One curved on top, one curved left, one curved right.

Sweeping with just the two side curved rails, not the top slightly curved rail, seems to generate one sweep, but top is not curved.

This is not an answer.
- Brian

Edit: now I see a gap at top of one cross section?
Both cross sections have a gap at the top.

The top curve does not intersect one end profile. It needs to be rotated.

Maybe the left halves of the profiles do not quite match the right halves?

Two rails are duplicated.