the lesson to be learned is how to close a runway in a way that is utterly obvious and clear
To clarify, are you inferring the current process isn't sufficient? in this case, NOTAMs, runway lights off, a lighted X on the closed runway, a clearance to land on the lighted proper runway, an instrument procedure that provides positive lateral and vertical course guidance to the runway in conjunction with an approach lighting system, differing colored lighting between runways and taxiways. likely a lot more safety nets as well. We should always focus on improving the system, but somewhere we need to focus on the most fallible part of the entire system, the humans.
I'm sympathetic to the AC crew and hope much is learned from this and that there's no negative long term consequences to their careers.