Anything that tapers in thickness should not really have a circular tiller, although the levers do mess thst rule up a bit. The whole idea of circular tiller in a pyramid bow is that the whole limb is evenly strained. The strain is exactly the same because it all is the same thickness and bends the same amount.
Basically, if you have parallel sides and circular tiller, the thick end is bending more than it should (which is where set comes from, which is bad close to the handle), and the thin end is bending less than it could so it weighs more than it needs to. So, even in a molly, keep thickness consistent and accept that the sides will taper some, or tiller in thickness, and accept that the bend will be pretty close to, but not exactly, circular.
The good thing is that because of the stiff outer limbs, just a very little of either or both will get a good tiller. In spite of what Huisme says, my mollies usually width taper just BARELY, maybe 1/4-3/8" over 60% of the limb length-ish, and then I touch up tiller with a little thickness scraping.