Chris is right, most major engine failures give ample warning - such as step changes in rotor speed or EGT - if someone is paying close attention to the data. The engine manufacturers have proprietary monitoring programs that chart engine health (based on such things as ACMS reports, or in the case of the newest engines on the 787/747-8 use downloaded data from dedicated engine monitoring systems that record data from start up to shutdown). If used, they can alert the operator it's time to get the engine off wing ASAP.
Many, many shutdowns have been prevented by these systems - however they are not perfect, and worse many operators don't bother to pay for their use (often a classic case of penny wise, pound foolish). No idea about JAL...
BTW, shedding a large number of blades is not uncommon when something large lets go upstream - not only do you have whatever let go, it creates debris as it hits blades which then creates more debris as it hits other blades. I once saw a picture of a PW4090 that had completely "corn cobbed" the spool (LP I think, but it was 20 years ago) - there wasn't an intact blade remaining on the turbine...