I don't have the same issue as you but my RSW's sometimes will not come on when it starts raining. I have to click the wiper switch one way or another to get them to start(sometimes)
And why didn't they hook the rear wiper into the rain sensing system
A small annoyance compared to your issue.
My Automatic high beams work flawlessly except for sometimes the reflection from street signs will cause them to go back and forth from high to low. I have the self leveling HID's
My XK is an 09 Hemi Limited