Doesn't that result in the brake being slightly tilted back because the bolt is not centered in the rear hole?
no , the flat back of the brake assembly, is pulled firmly against the flat front of the fork crown and with sufficient torque on the bolt it doesn't move
tried one of those nylon bushings like RBW sells .. the brake moved more because of the softness of the bushing..
Were that made in Metal that may be less of an issue..
Specifics .. Brake: older Campagnolo Record.. single pivot., Frame/fork : Bridgestone RB1.
in use for 22 years, now..