Yeah there is problems with the RNG method, mainly it tells us the attack order goes with Sheba first, but in the second round it has Felix and Jenna attack the Sky Dragon, when Sheba has already unleashed a Jupiter Djinni, and because of such it is already dead. Furthermore, the method in my practice did not yield an Orihalcon. I think we should replace it with the method from Link Kirby's RNG faq from Gamefaqs:
Attack Order: Sheba, Jenna, Felix, Piers. Encounter a Sky Dragon and one other enemy.
TURN 1 Sheba casts Spark Plasma! Big Arrow on Sky Dragon (or similar area psynergy) Jenna casts Aura! Felix casts Grand Gaia! Big Arrow on Sky Dragon (or similar area psynergy) Piers casts Megacool! Big Arrow on Sky Dragon (or similar area psynergy)
TURN 2 Sheba unleashes Squall! (or similar djinn)
Deal with other enemy any other way.