Maybe it's something, that has been reported before, but I haven't came across of it, so I'll let you know :)
When you convert a Vray material, that has reflection, and Fresnel reflections is enabled, but the amount of it is controlled by the refraction IOR value (refraction is disabled), than after you convert the material, the CoronaMaterial has the default 1,6 IOR value for reflection and has the refraction IOR at the refraction part.
So if somehow the converter could detect, if the Fresnel IOR value is "locked" to the refraction IOR value and is controlled by it, it would be nice :)