Do Airbus pilots have to practice flying in alternate law?
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.