The FOHE (Trent) was not specifically designed as a fuel heater/ice melter.
I can't stress this enough. Modifying an existing component to mitigate a problem its overall design was never meant to address is unusual, to say the least. In the absence of further work on fuel/fueling issues, (is there any?), the actual cause of the icing induced rollbacks is being neglected?
The ICE is not the cause, it is what causes the ICE.