So the discussion enters its
fork in the road. To damp the energy within the piping, absorbers,(damped mounts) must be tuned for all forseeable mechanical vibration. To that extent, a certain flexibility needs to be engineered into the mounting of the piping. But wait, if there is too much, the Pipe and Fuel can act in unison, which would conceivably block flow. So what is the design of the pipework relevant to the contained and flowing Fuel? And let's not forget forces other than resonance. Like Harmonics, Flutter, coef friction values dependent on fuel type and source. This is getting interesting.
Airfoil
At the point of entry of this discussion, system isolation and ETOPS are frankly irrelevant. Two systems on separate A/C could behave identically with one another given the ineluctable power of certain anomalies and reasonably similar parameters. Lose the seductive and nonrelevant impetus of ETOPS, or lose the basis of debate. This isn't about how incredible it is to entertain the thought of concurrent failure anymore, it is a given.