From the NTSB press release posted above :-
"......... These recommendations are being issued in response to the findings in two investigations - an accident and an incident - involving engine thrust rollbacks on Boeing 777-200ER airplanes powered by Rolls-Royce RB211 Trent 800 Series engines. In both cases a build-up of ice (from water normally present in all jet fuel) on the fuel/oil heat
exchanger (FOHE) restricted the flow of fuel to the engine, resulting in an uncommanded engine rollback. ............" (my bold)
Fascinating.
According to this, the two investigations have been completed (at least they have specific "findings" and are factually known) as opposed to theories or speculation !
Likewise, they have supposedly explained where the additional water came to cause the problem.
Unforunately they haven't bothered to highlight other engine installations in other planes which need similar flight restrictions.
.