SO for instance, with the first model you posted, I ran that script on it and see this:



So I zoom in to the first area and delete this face, then select the 2 edges and run loft. And join that new piece to the rest. Actually the same for the other side piece which shows naked also.



Then the next piece is this front edge. I delete the under neath surface and then run sweep, using the 2 curves as profiles and the 2 straight edges as rails, then join that new surface to the body.



Then the next edge is here:



Since it crosses over multiple edges, I delete all 3 across the top there, then select all these edges and run Join on them.



Then I run sweep using the 2 end curves as profiles and the to joined edges as rails, then join the new surface to the body and it is solid. Remember not to join the edges in with the surfaces when selecting for a join