I’ve felt some of your pain, too with Engine crashes (need to manually tweak engine settings and registry keys to stabilize), but IMO UE4 is the best game engine available for indie developers today and C++ is by far the greatest programming language ever created (thanks Bjarne!). Yes, both are hard to learn, but with some patience and hard work you can create something amazing.
For the USTRUCT problem and similar issues, I strongly suggest looking at how the UE4 samples/tutorial projects and engine code itself implement things.