That's a brilliant analysis of the papers from 2014 and the current one. This makes me wonder what was the exact reason behind the restoration of metacognition in one study Vs other. I couldn't say if they have a big difference in their methods. However, like you said they had brain lesions for different reasons. This curiosity is bugging me a lot.

Anyhow, this also reminded me of phantom blindness mentioned by VS Ramachandran in his book "phantoms in the brain". In that case, victims who have suffered some sort of brain injury can see, but they can't know that they can see. For instance, they can in quick reflex pick and pass the largest or smallest box on the table but can't know that they can see the box. It's been a long time since I read that book, but I think, in this case, the visual cognition for knowing that they saw an object was in a different region of the brain (I will go home and confirm this later). So there is a likelihood that different kind of metacognition processes are distributed across the brain?

Also, I remember reading this article long ago. But he seems to be doing ok in life. It seems as if the neural networks in another place can learn to do the same tasks, as your post suggests. However, the question that's bugging me when it does and when it does not? Anyway, I will go and read more on the topic. Thanks for sharing this wonderful post.