A big element of this endeavor would be the ability to guarantee valid types only. Meaning, I should not be able to accidentally use the higher level API to create a square with 5 sides, etc. So, whatever constrains are imposed by my primitives remain. If the higher-level language would also let me prove properties about my specific geometrical object after a series of operations that'd be a huge plus (although I have zero knowledge of this domain). For example, if after some operations (unknowingly to the user) they change a mesh in such a way that it now satisfies conditions for a Delaunay triangulation then it would output a message saying this is the case. Alternatively, given some mesh I should be able to specify "make it X" and it would automatically apply the operations (based on a selection of suitable algorithms) on the mesh that would guarantee that the output does indeed satisfy X.
@wilfredh you seem like the kind of person that might know about this stuff