The CellData and PointData aren’t the cells and points, they’re collections of named arrays that hold data values (e.g. colors, temperatures, directions, normals) that are associated with the points. As far as I understand, these arrays are irrelevant to what you are trying to achieve.
If you want to get the points and polys from the output, why not just cast the output to vtkPolyData and call GetPoints() and GetPolys()?