My take is that there are lots of good questions and good postulations among the clutter in this thread.
We still have too little confirmed data and as such lots of interpretation of what little data is available.
The good and the bad of it is that there has been no smoking gun of data prior to this event that gave us a clue that this was going to happen, Sure there have been incidents (things fail) but nothing that pointed at a likely event such as this. Independent failures of the certified systems between the aircraft and the engine are unheard of in this generation of design. So the first place I would look would be either a dependent failure or a latent failure in combination with another failure condition. The latency could take the form of a safe guard or layer of redundancy that was missing and/or not detected, The other parts of the chain could be simple gotchas for any reason including crew performance leading up to the initiation of the problem.
So we need to be open about the investigation in a technical sense whilst tolerant at the same time of the human element after the fact. (no blame)
I'm still struck by the differences in the visible dirt ingested between the two engines. The one engine with the dirt stuffed into the core compressor sure appears to have been at high power.
My question at this time (which I'm sure the investigators alread know) is whether the engine (s) did actually spool up belatedly. Putting this question to rest stiffles an awful lot of speculation on this board todate.