Crix:
Well the problem is that it is not my house and I think I am not allowed to modify/change this. So I was thinking of some kind of 3D printed object to hold the servo or motor
Could you mount a piece of aluminium or brass strip or sheet under the escutcheon and bend it over to make fixture for the servo without damaging the escutcheon. Many model shops and model engineering suppliers will have suitable material.
...R