Unimportant side question: why are they called "macaroons"? I find that a bit offputting in its cutesiness, and the word doesn't even give a hint as to what they are (aside from being a flavor of cookie, I guess).
I suspect you have answered your own question - historically cookies in the browser have been one way to identify and control what a user can access, I'm guessing authors have continued the small baked goods theme in naming their own access token.
Now, if I had to guess, this are "a new kind of cookies" so they just took a name that went with it (like they did with biscuits https://www.biscuitsec.org/)
There are many chances that they got he name wrong and they meant Macaron (with one O instead of two). Those are "layered" cookies, which bring some resemblance on how "caveats" can be understood.