There have been ~5500 A320 series delivered. They do, say 3 sectors per day, and 1 "daily service" opening the cowls. An engineering team might meet say 20 (?) aircraft on an evening shift to service overnight.
There have been ~15 "loss of cowl(s)" incidents, nil accidents
AFAIK (although that would require a close look at the definition - NB damage to engines and cowlings is not counted).
Is a repetitive paperwork, or rigour, exercise going to solve the issue? In times of cost/manning pressures? Or are these very rare "slips" better solved by trying to easily highlight the problem prior dispatch as previous recommendations have stated (and been ignored)?