Why do you talk about “C”? UE4/5 is written in C++ to make use of the OOP features. C does not have OOP features by default.

Just look at this very basic class hierachy:
image

If I change the default value for a field from “AActor” ALL the derived classes will be affected unless they override these default values.

Looks like either Funcom has diverged from the standard UE development principles or you seem to not understand how UE works or game engines in general work.