well theoretically you could argue the structure of this task should have 'dual control' / multiple people should be involved in the process checking each others work. preferably even split it up people who do not know or interact with each other on a regular basis. yes it would be slower but its important to get it correct.
might as well throw in some automated poke-yoke or whatever too.
in that case there is no fault in any of the juniors or operators, the fault is in management for failing to implement infrastructure to force a critical process to have more than one control
And if not, whoever put the junior in that role is the person responsible for the problem.