Add Impulse and torque will have some issues because you are pulling / pushing against the constraint, so it won’t be flying straight back for instance since the constraint location will be closer to the handle, is actually correct behavior, but you’ll be hard pressed to get it really clean compared to a logical approach.
As for the addition transform, it is a base transform that is applied to prior to the wanted grip transform calculation, so it adds an offset to the final position / rotation that is passed out for the object to attempt to move towards.
If you DID want add force you would have to apply it after all grip movement and likely would want to total it up yourself, because each tick the grip is going to be attempting to re-orient itself to where it should be.