I think Stefan you should complain to microsoft about that. Microsoft made that very convulted system for storing user data, they change it with every new windows and keep backward compatibility. With new UAC thingy that is security protection windows style it only annoys users and programmers and its child’s play to circumvent it (if you do not care about stability of your code like malware authors). You see there are probably reasons epic uses what microsoft recommends, and ms recommends user data folder. So here i rather blame microsoft, epic coders just follow guidelines for your system. Only real solution is to get bigger SSD for system.
I also hate when my PC knows better what i want to do, like being stubborn with storing huge stuff on drive C, or preventing me from saving on C:\ while every other app can do it, or changing how folder attributes behave so some older apps refuse to work on win 10 properly. There is a lot of stuff like that.