This is how you should be able to replace the ‘get all actors by class’ node. You get the player controlled pawn (which should be of type ‘HorrorEngineCharacter’). You cast to said type, and the get the child actor component, which is just an other variable.
To make sure your widget actually exists, you can check if the reference is valid, this should be used inside the confirm event functions as well as the mouse wheel function, inside the player blueprint. Just connect everything with the exec pin.
I guess you called the old ‘On Mouse Wheel’ function from the ‘On Mouse Wheel’ event inside the widget blueprint, and you made sure the function gets called?