Rare encounters ? yes
But obviously the results can be so severe, the encounters must be either eliminated or mitigated by the engines, etc.
I may be mistaken but I got the impression that the crews initial actions were in response to a serious event already underway.
Is there something they should have done before hand ?
From the engine standpoint, with the latest knowledge, the problem is actually aggravated by the increase in temperature as the air/ice gets compressed in the engine. It turns the ice crystals into little stick pellets that stick and accumulate to surfaces long enough to build up layers, temporary in nature.
The problems comes in when these temporary sticky buildups dislodge and cause downstream damage to the high speed compressor section, or screw up the airflow enough to cause the engine to surge or spool down.
Engines at high altitudes are quite sensitive to changes their FADEC logic wasn't expecting.
Given a chance for being activated, engine bleeds are your friend.
The FADEC logic actually has more to work with than just what the pilot senses from aircraft sensors.
For instance, the RPM and temp matches between the engine spools might be sampled fast enough by the FADEC to activate bleeds before the engine stops working.
The theories are there to be used but the verification may not be easy nor quick.