Re: Bump Steer
I'm with Falcon on wheel offset, magnified by wider tyres.
I get a different response in the steering wheel going over a parking lot speed hump at an angle.
First the outside edge of one front tyre strikes the bump first, then soon the inside edge of the other tyre - different amount of steering wheel torque. Would indicate offset as not ideal (given L&R caster, camber and toe are the same).
Are your wheels stock ? What are the tyre dimensions? I looked long and hard to find cheap aftermarkets that had offsets similar to stock. Settled for 17x7 on the front and 18x8 on the back, yes driving downhill.
Also what targa says is true, returning the car to original height will help also.
If you lower a car, then all the geometry changes. There are compensating blocks that can return the control arm angles to original, similar for steering (tie rod) angles, but the factory dialed in the macpherson struts and wheels pretty well, perhaps a little soft. I've got Eibach springs and they are firm, gotta slow down over bumps or it is unpleasant, but with standard sway bars I have very little roll. It hooks around bends nicely.
The compensating blocks I mention help reduce body roll.