MCAS strikes me as the low airspeed variety of stall risk case. The high airspeed case is rare, and trained for aerobatics and flight instructors. The low airspeed case is taught on day 2 to student pilots, both power on and power off varieties. MCAS is reported to not take airspeed into account, therefore it must apply a one size fits all correction, which if useful for low airspeed approach to stall would seem to be overly aggressive for high airspeed.
AF 447 airspeeds were regularly below 60 kt. That's not a high airspeed stall. The final report is ~223 pages long, it's rather complicated to summarize, BEA blame practically everyone for something including weather, software, simulators, training, and pilots. As a pilot, some of the Airbus system behaviors in this case really piss me off to read, just how aggregiously badly designed it is when it gets confused, papered over by dumping the consequences of failed automation and the ensuing alternate laws onto the pilots. The pilots' job is system admin and troubleshooter. If they fail, they will be partly blaimed no matter what, because that's the job.
From the AF 447 final report: a) Both pilots were shocked by the autopilot disconnect. b) Reconnect of autopilot prior to 30 seconds of stabilized airspeed indication can result in pitch runaway and an unsafe condition. c) stall warning sounded continuously for 54s, neither pilot referenced the warning or stall buffeting. d) absence of any training, at high altitude, in manual aeroplane handling and in the procedure for ”Vol avec IAS douteuse” which you allude to. e) theoretical training for the pilots associated the buffet with stall and overspeed, even though in reality buffet is only encountered with stall. e) when there are no (software) protections left, the aeroplane no longer possesses positive longitudinal static stability even on approach to stall.
It's just crazy, only somehow partly neutralized by the statistical fact air travel is still really safe!
AF 447, last recorded values were a pitch attitude of 16.2 degrees nose-up, roll of 5.3 degrees to the left, a vertical speed of -10,912 ft/min, ground speed of 107 kt, and full power. And for the last 11 seconds "sink rate" and "pull up" warnings sounded. No emergency transmission sent (quite common).