If you are importing and not seeing your cliffs, that means your other weightmaps are strong enough to cover it up.
And for the sand, it means your blend modulation may be a bit strong. It is expected when applying blend modulation that the apparent edge will move away from the original edge… Try removing the modulation and plugging in the straight blend. Then you may want to consider doing an additive scalar param offset before you do the 512 contrast multiply. My guess is that the large multiplier is pushing your alpha values mostly out of range.
That is just the nature of height blends. You take a soft masks (which is the worldmachine layer) and then increase the contrast using some other tiling texture (the sand height). The desired goal of that is to make the blend sharp but it can mean that only a certain value shows up. You won’d be able to see a soft feint sand, you are purposefully making it all or nothing.
“Not using splatmaps at all.”
Splatmaps is just a generic term for using masks inside worldmachine. Any time you render out a single erosion map technically you could refer to it as a splatmap. Typically it refers to channel packing the masks into one texture but that distinction is a bit meaningless when we are talking about landscape since you cannot channel pack the masks in a traditional way.