Is it possible that fuel from Chinese sources is more prone to icing than fuel from UK or US suppliers? Presumably, the investigators will have compared the molecular composition of fuels from various sources using mass spectrometers and found no differences. If so, it seems strange that both instances of roll-back occurred on flights FROM China and none have been reported on reciprocal flights TO China.
Mitigation of ice formation by redesigning pipework/FOHE is all very well but the real long-term answer is a fuel which is free from significant ice formation under all imaginable flight conditions.