Hi Mala, those pieces that poke out on the sweep are places where the path has a sharp corner in it instead of being tangent smooth.

When there is a sharp corner sweep will try to construct mitered corners by extending the sweep surfaces on either side of the sharp corner and intersecting them with each other. That corner mitering process can be difficult when performed on a non planar path.

So the main way to fix it would be to tune up the rail curve so that it's all smooth instead of having sharp corners in it.

- Michael