You wrote “Metacognition seems like a technical term which isn’t defined”, which reads like you weren’t familiar with the term. It’s not a particularly exotic or ill-defined term.

Metacognition doesn’t just mean thoughts about thoughts, it means perception of and thinking about the process of your own thinking, about its mechanisms. It’s recognizing and reflecting about how your mind works.

It seems to me the author of the article is using “metacognition” in the normal meaning, so I’m not sure what the problem is.