I think this is rather important. I get the distinct impression they also called for single-device cheating methods; almost all of the cheating methods employed

I think this is rather important. I get the distinct impression they also called for single-device cheating methods; almost all of the cheating methods employed are unrealistically complicated and prone to detection: but you could just use another device (phone, laptop, whatever), and be vastly less likely to be detected or flagged as suspicious. (The only thing that might remain troublesome is ones where you want to speak to someone or play a video, so the microphone shenanigans might still be employed.) In practice I feel like this isn’t even “it failed to detect all six cheaters” but rather “it failed to detect all six cheaters, even though we got them to cheat in ways that are uncommonly detectable and there are much easier ways to cheat that it has absolutely no hope of detecting”.