The viewport is displaying a section of the geometry using the sectioning tools found in the latest V5 WIP.
To do this just create spheres on each point using the desired radius and booolean intersect them with the voronoi cells. Use the grafting component on both lists before inputing them in the boolean intersect component.
i 'm quite new with this stuff and i can't quite get the "grafting component" part..before the boolean intersect component....so i would like to ask if it's possible for you to post a printscreen of the def.