PJ2
My casual observation of this monstrous thread is that engine issues have been remarkably lightly addressed. The first time I noticed it quite some time ago, you may recall, I brought up a severe yaw causing blanking and at least one engine failure perhaps as a result or cause of VS separation.
That aside, EASA have noticed a probable (?) extension of the Trent 800 AD relative to rollback resulting to the Trent 7 and 5. Regardless of type, Icing pitots would certainly suggest other Ice related issues, to extend to core or even fuel path. Relative to ACARS and engine data, it seems unsupportable to embrace only one narrow Ice induced possibility, at least to me. Perhaps there was no 'upset' at all, merely a long descent (to include either rapid or reasonable RoD) ending in an unpowered and failed entry into the Sea. Is there some amount of intelligent speculation relative to eliminating this possibility?