Does idebenone, an antioxidant, may help the F A-affected heart.?

Yes. Small studies showed that it helped thin the heart walls by a small amount, with minimal, if any, improvement in cardiac function.
That’s not to say that idebenone is the wrong way to go. Idebenone for a lifetime may be very effective at maintaining heart function. We don’t know until these clinical trials are conducted.
But as a cure, idebenone is not it.