I complained at LAX about the wheelchair brigade delaying folks in the Pre-Check line. It took 2 complaints but now if there are Pre-Check folks who walk up before the wheelchair folks are out of the chair, you can go in front of them. Before you had to wait behind all of them.
My other complaints were at various airports for lack of getting Pre-Check. Each time they opened an Inquiry with TSA, and one saw I had 2 opened already, and escalated it to a section in TSA who worked with the airlines to get it working. I have not had anyone rude, had anything come up missing, or any other issues than those. Since it was the Managing TSA Officer at the actual Airport each time that replied, I am assuming they are the ones who check the boxes or reads the cards, which is better than the TSA person who is standing there doing the screening.