Generally book or a rock should be implemented as Pawns. Actors are more generic than gameplay objects. Actors are good for noninteractive decoration items. And Pawns are for everything more complex.
I think i’d start with making some common actor or scene component, which will implement all the logic of firing OnInteract events. And add it to all my gameobjects. Than there should be interface to get to this component.
Of course there is always the option to get the source code of UE and add needed functionality to base classes, but I’d avoid doing this. It is easy to build UE yourself, but changing base classes is an overkill.
Check Fortnite, UT and ARK devkits - these are games based on UE, I dont think they are chengin the Engine too much.