Does this build work the way I think it does? Lock primary target, use cluster missiles. Use cluster missiles against secondary target, cancel dice, recover charge. Trigger pilot ability for second attack on primary target.

Double Edge - After you perform a [missile] or [turret] attack that misses, you may perform a bonus attack using a different weapon.

Cluster Missile - After this attack, you may perform this attack as a bonus attack against a different target at range 0-1 of the defender, ignoring the [lock] requirement.

Munitions Failsafe - While you perform a [missile] or [torp] attack, after rolling attack dice, you may cancel all dice results to recover 1 [charge] you spent as a cost for the attack.

You're limited to a single bonus attack per round. While Munitions Failsafe cancels the dice and returns the charge, you still performed an attack. Double Edge couldn't perform yet another attack.

That would be the catch, thanks!

I think, that Munitions Failsafe will not work with Cluster Missiles. You spend the Charge to perform the initial attack and then for free you can perform the bonus attack. The card says clearly "(...)you may cancel all dice results to recover 1 charge you spent as a cost of this attack." As you did not spend a charge to perform the Bonus Attack, I would argue against such ruling.

Edit:

NVM! I'm an idiot.