Hi Adam, currently there isn't any way to switch a corner point into a smooth point but it is something I want to add in.

Right now you can delete the corner point and add in a new smooth point if you want though.

Looking at your sweep.3dm file, changing the node type would probably not be suitable for your particular case as-is because one of the curves has dense control points. Switching a point type could make it smooth but there would be a really tight bend in a small area.

- Michael