This will require some detailed explanation why would that be really hard to do.
STL is a mesh format. This means, that it contains a list of triangles, that represents the 3d model.
Shapr3D is based on boundary representation. This means, that it works with parametric surfaces and curves to represent shapes.
Creating triangles from parametric surfaces/curves is straightforward, and fairly easy to do. The other direction is not. There are some 3D software that supports this (more or less), but implementing this functionality would be extremely complex.
So the short answer: probably we are not going to be able to do this in the next few months, but I see a little chance, that we are going to support this later. But currently this is not even on the roadmap.
We are really happy that you are enjoying Shapr