When the asset outputs NURBS surfaces, they are converted into polygons. By default, the conversion uses the LOD method to adaptively changes the resolution of the output polygons. This prevents the polygons from being too dense. However, it causes the sudden changes that you're seeing. You could prevent this by simply outputting polygons from the asset. For example, you could 1. If the circle SOP is outputting NURBS curve, then sweeping will produce a NURBS surface. If you change the primitive type to polygons, the result of the sweep will be polygons. 2. Or, you could add a convert SOP to after the sweep. This lets you convert the NURBS surface to polygons manually. This lets you control the options that are used in the conversion. Using “Divisions per Span” will give you more consistent output.
Take a look at the attached HDA for an example.
When I have a chance, I can look into adding a parameter onto the Maya node to control this conversion process.