Lyman, Im not certain what you are asking. In my opinion, NAVADR is insufficient because it points to NAV. NAV might make perfect sense to the engineer who designed the systems, but to a pilot - NAV is NAV. Airspeed, vertical speed, altitude...those are not NAV. The Autoflight disconnected, that's not a NAV problem.
Additionally, NAVADR requires interpretation, it requires recognition. A NAVADR annunciation complicates the situation. IMHO, AF447 would have been better off with NO ECAM. Then, at least, Robert might have diagnosed the true environment rather than be a slave to performing ECAM actions.
Yes, an isolated cue for UAS would be desirable.
Since all pitot inputs are fed into computers, I'm not sure that a line abreast display would make any difference. That's one of the things I've tried to relate to the non airbus pilots in this string. It's ALL computer generated. Who knows what to believe? The only thing a pilot can truly trust is what he sees out the front windscreen.