More battle damage and a nasty scare

[powerandtorque]

Tracking is pointless, as there is no adjustment there, just check for any movement

Poor advice IMO.

You can quite easily bend a stub axle with a sideways impact on the rear wheel which will throw the rear wheel alignment well out but there not be any play or movement in it.

Depending how far out it is the car might just not feel "right" or it might be complete liability, plus you're likely to have brake issues on that wheel too as the caliper and disk won't be running true to one another. It can be out far enough to noticeably impact driving and yet not look out by eye, particularly when the surrounding bodywork is bent.

You might not be able to adjust it as such, but if you take it in for a tracking/alignment check and the alignment values are all over the shop then you know that it needs a replacement stub axle (or complete arm)