Understood, thanks.

I'm curious whether there is another program out there that can create accurate models with vertically stacked contours.

I have very accurate site contours for a large, hilly site. The contours were drawn by a civil engineer and show the proposed conditions, including many vertical retaining walls. I have used TopoShaper to generate terrain from the contours, but it (like the default SketchUp version) doesn't seem to be able to handle vertical faces. See views below of contours and Toposhaper results:

Clearly a lot of detail is being lost here. Does anyone have any suggestions for how to handle this accurately?

@Fredo6: Thanks for your work creating this.