Do I understand it correctly that the green bowl uses both materials with and without bumps? If so, then this is expected result - because there is no way to tell, which side of the material is which, so corona has to assume. And the assumption here is, that if you enter glass through face with one material, you cannot exit it through face with another - even if it is basically the same one, but with bump. So the second face also "enters", not "leaves". So what you have is a scene where there are two glass objects inside each other.
You can either use the same material on both sides of the object (you can for example map the bump map only to one side), or fake it by disabling the attenuation on the inner material.
In future I plan to add a feature to optionally manually specify which material is on which side of the face (w.r.t. surface normal)