What I was alluding to was procedures/techniques to spot when the aircraft, which is following the box, is going off the rails ie diving below the required profile between waypoints.
Re the company checking, I understand that some check the database before flight use using a checking program.
Is it conceivable that this sort of database error (if it is the problem) could occur on a RNP-AR/SAAAR approach where there is no way of checking the profile altitude/distance down the approach apart from perhaps total track miles to run (if it is displayed somewhere?).