IMHO, pilots didnīt fail to recognize their compromised situation.
Rather, I think they were dealing with a confused system, which missed the right
"law" switch or state change to begin with!
Bad training (read = arrogant position taken by manufacturers and company policies), contributed for sure!
The training based on following automatics improved the waste of time, wich at the end killed them all.
When the Captain reentered the cockpit the power plant was set at idle and nose-down inputs were fed...
So: Why?
Why power idle and change of pitch?
Well, I think they knew (or the Captain did), the best way to make a compromise with the (for them unkwon), airspeed was to make a glider of the aircraft.
Going back to the basics thus...
They just missed the Trim Wheel... And when they were on the right path to solve the problem, automation began blaring stall and confused them even more...
Who knows... Maybe it was far more worse than we can imagine...
I my eyes they knew their status, only FL370 is way to short to react well when your rate of descent is 10K feet/m.
And... If I had been a pax on AF447, sure I had tried, crawled on the roof if needed, with all the negative gīs on my ass to the cockpit to tell the pilots they had to decrease their AoA as soon as they could...