Im not brilliant with this but…
if you want to return reference in blueprint I think you want
FEntityAttribute& GetTargetAttribute() { return targetAttribute; }
if you want a pointer i think you want return a type *FEntityAttribute **not FEntityAttribute&
i believe blue print function parameters need to be **const FEntityAttribute& out **I think as well for your second try
this seems to show an example of native with a pointer
https://wiki.unrealengine.com/Bluepr…ntNativeEvents
also maybe see this post
hope that helps (and i hope i got that right)