Considering the first thing we here is a board member talking to Mr. Afton about the design choices, who in their right mind would continue to use these, or fail to notify others that they were being used?

The only possibility i can think of is that afton somehow convinced them that the designs were not as malicious as they seemed, which seems tricky when the blueprints themselves seemingly have children inside of them.

I said it as a joke in an earlier thread, but what if he convinced the board that the storage was for child protection? Given that the company has a history of trying to implement features to improve "safety" of the restaurant, i don't think it's too far fetched he might have convinced them that, in the event someone tries to harm the children, the animatronic features could be used to distract the attacker and lure/lead the children to safety.