A similar situation occurred to a Jetstar 787 into Osaka a couple of months ago. Both engines indicated eng fail on EICAS but then auto recovered. I get the feeling that the engine manufacturers are walking a similar path to Boeing and the 737 Max. The line pilots are becoming test pilots because the corporations don't want to spend a lot of money on flight testing. Bring ETOPS approvals back to 180 minutes and see how quickly things get fixed.