Hi,

The problem is on your construction of your curve with hard corners very near.
Is it normal that your curve is not planar ?
You want it or is it an error during construction ?

If it what you want, you can use the ReconstructCurve script to have soft curve non planar. 200 points are ok for example to have nice sweep.

If you want a planar curve, resize it to have a flat curve. The sweep will be OK next.