Really sorry to hear what happened but sounds like you're getting everything sorted. A rear facing dash cam would have been revealing as to what the driver was doing.
I did a bit of rear panel and bumper damage to my 05 RX a few years back. I thought it was all fixed fine but then started noticing a bit of wet in the rear foot well carpet, When I got all the trim etc. off that lines the boot it was soaking. I'm sure a Lexus approved repairer will do a proper job as opposed to my back street guy. Be worth a bit of investigation after a heavy downpour or a hose to make sure all is as it should be. Best of luck and hope you get her back soon.