Do Airbus pilots have to practice flying in alternate law? I am sure when getting their type rating for Airbus FBW aircraft, pilots learn how to fly in alternate and direct law. After that, how much opportunity do they get to practice this skill?
On Air France 447 and Indonesia AirAsia flight 8501, the A/P switched off unexpectedly and the control law degraded to alternate 2. It appears in both situations that the PF had trouble stabilizing the aircraft roll attitude. It's difficult to determine whether this contributed to the pitch up and eventual stall but the original pitch up command may have been inadvertent while struggling to level the wings.
Under normal law, which pilots are accustomed to flying, the FAC calculates the amount of aileron deflection required to turn the amount of lateral sidestick deflection into a rate of roll with a maximum of 15° per second. In alternate 2 law the computer cannot make these calculations so it becomes direct stick-to-aileron control.
This can mean that the aircraft responds very differently than what the pilot is used to. Sometimes the difference may be slight but at high speed and high altitude the same stick deflections can result in a significantly higher roll rate.
Additionally the stick does not provide tactile feedback as to how much force is required to move the control surfaces. With conventional flight controls &quot;roll or pitch rate would more directly correlate with the force applied on the control wheel, and not the amount of deflection required.&quot;1
These things combined can result in the pilot over-controlling. The control inputs can get out of phase with aircraft movements resulting in pilot induced oscillation in the roll axis. This occurred in both of the above accidents.
It must be terribly disconcerting for a pilot when the A/P disconnects and they are handed control of an aircraft they fly every day, but doesn't respond the way they are used to. I'm wondering how much practice they get at flying in this configuration, either in a simulator or in the aircraft itself. Do most airlines flying FBW aircraft require this regularly? Does Airbus - or anyone else - recommend any amount of further training or practice? Have these recommendations changed in light of the accidents?

1Bill Palmer, Understanding Air France 447
It appears in both situations that the PF had trouble stabilizing the aircraft roll attitude.


Note that roll control is secondary when recovering from a stall. 


  Restoring normal pitch and roll, he stresses, are "of secondary importance"


The situation required that the pilots heed the stall warnings, be aware of the stall and put the nose down to trade altitude for airspeed.


  Have these recommendations changed in light of the accidents?


You can read the recommendations in the official accident reports. These usually explicitly state what such changes should be. I believe it is very rare (except when investigators disagree) for regulators, manufacturers and airlines to ignore any such recommendations.


AF447
QZ8501


From what I recall, the major problems in these two incidents were not that the pilots were simply unfamiliar with how control inputs affect flight in alternate law. major problems were that the pilots did not seem to be aware that they were in alternate law or even aware that the aircraft was stalled. In both cases the pilots were confused, failed to follow procedures and failed to coordinate their actions effectively (i.e. CRM failures)

Airbus Flight Crew Training Manuals do cover alternate law.



Recommendations included


  5.3 Aircraft Manufacturer
  1. The KNKT recommends that Airbus to consider in developing a means for
  flight crews to effectively manage multiple and repetitive Master Caution
  alarms to reduce distraction.
  2. The KNKT recommends that Airbus to consider and review the FCTM
  concerning the Standard Call-Outs in all phases of flight.


The Indonesian report lists  in some detail the actions taken by the airline and includes an Airbus article "What is a stall? How a pilot should react in front of a stall situation". It also includes some guidance issued by Airbus which includes recommendations concerning upset training in various control laws




  After that how much opportunity do they get to practice this skill?


This depends on airline (and relevant regulators) more than on manufacturer. Upset recovery is probably something that all pilots should be trained in, and maintain familiarity with, regardless of who manufactured the aircraft.