The reflection system in Unreal is “mostly” a one way thing. it isn’t impossible to pierce through it, but it gets messy, and is prone to Runtime String Resolution “problems”. Unless you are making an editor utility specifically to work with Blueprint stuff in C++, or you are 120% sure the things you are looking for in the Blueprints “WILL NOT CHANGE”, you are better off treating Blueprints as child-classes that just graduated high-school are responsible for themselves with the ability to phone home to the C++ Parents.
the short answer is: if C++ needs to know about something specific: Enums, Structs, Classes their base version should be defined in C++.
you can take a look here for more details.