The backlogNothing is wrong with your process. There's just too much of it.
Schools that take teaching quality seriously already do this properly — record the class, sit down with the footage, score the instructor line by line against the in-house rubric. It works. It's also the single most expensive hour in the building.
At forty minutes a review, a supervisor gets through a handful a week. The rest of the recordings sit on a drive, watched by nobody.
Woggle reviews all of them, on your form, and flags the ones a person actually needs to watch.