every Pole feels entitled to his or her own version and its ad hoc contortions.
Yes and no. Those contortions you mean are basically a parody of infant`s first utterings. Boo - boo, goo - goo, are the easiest sounds to produce. Foo foo is more difficult that is why it isn`t in the list that you proposed.
That is why we can say bubuś to a baby but not fufuś. Do you get the drift?
Have you ever taken care of a baby longer than on hour, e.g,, when your wife was ill or sth? Probably not. :):):)