Can you please send through the scene(s) in question (before the conversion) and we will look into it.
Well... there is nothing to send :- ). The Converter doesn't account in any way for "Reflection" slot because new Material doesn't have one, and nearest equivalent is IOR. But mapping (Clamping) reflection shouldn't be considered "fake" per se and rather translated into IOR. Plenty of dielectric materials require mapping reflection to create illusion of depth.
Real world materials do indeed only vary roughness and surface relief, but with CGI Shaders we're faking information that geometry simply doesn't have. With that in mind, even mapping reflection is physically correct to real-world matched counterpart.
There is thread somewhere else on this forum where work-around was found in different ways, most common simply mapping IOR with Mix-Node. Dubcat did lot more complicate OSL setup, which sadly isn't universal enough (Since majority of 3dsMax don't even feature OSL and it could introduce lot of perfomance issues).