The Reinforced Smooth Quartz Block looks like the Reinforced Quartz Block.
Here are some images, on the right is Smooth Quartz and on the left is Quartz.
(I am testing this on 1.16.5)

The first image is with shaders and texture packs.

The second image is without shaders and no texture packs.

This is normal quartz, this is what I would expect it to look like, but still be gray/reinforced

I would appreciate it if this issue was fixed, thank you for the great mod!

Thanks a lot! It'll be fixed in the next update of the mod. In the meantime, you can use this resource pack to fix it:
sc_smooth_quartz_fix.zip