The sweepProfileConverter node is a secondary to the sweepMeshCreator node, created when you use the Custom Sweep Profile shape. See Create a custom mesh with Sweep Mesh and Sweep Mesh options.
You can use the sweepProfileConverter to remove existing profile objects or components. When set to Curve Object, it can also be used to define the detail of mesh relative to the profile curve.
You can adjust the Curve Precision attribute can be adjusted to increase or decrease the number of subdivisions across the width of the path.
You can enable the Curve Optimize attribute to control the density of the Sweep Mesh along the profile based on curvature: straight sections will have fewer divisions, curved sections will have more details.