I believe I noted in the very post that you quote that I learned they are (slightly) different things, and that therefore it was not the best possible example of the phenomenon to which I was referring, merely the one that first came to mind.
If you would prefer a better example, how about when people use the phrase "a certain je ne sais quoi" to describe a positive quality that they don't have the right words for? It literally just means "I don't know what," but in French, so why not just say that?