Working fine for me. I think your issue is actually that you’re feeding a list of colors instead of a color for each surface. Enable previews to confirm.
I found another way around it though. Since I wanted this for Fractal, I kept the red one when area exceeds requirements, and for when the area is within the desired value, I fed the original surface in order to cause the error on the Display.BySurfaceGeometry node so it can display the actual Surface.ByLoft geometry. And is working fine for now Here’s a screenshot of it