First of all, wind. You’re going to need a lot of wind. There’s an Elements - Wind set, or you can pull wind from Icy Wasteland or Desert. Second, is this an Eberron-style airship? If so, it’s powered by a fire elemental, yes? If all that is true, pull ye from the Elements - Fire set, so we can hear the crackle of the flames as things get out of control. If it’s a modern-style airship with some sort of engine, may I recommend Sci-Fi player’s Car Chase - 1920, and the car engine therein?
For the harpies, there’s a harpy monk battle in Into the Valley (one of the Rise of the Runelord sets), with some harpy songs and hisses. Pathfinder Playtest 4 - Mirrored Moon 2 has a roc battle, with wing flaps, bird cries, and weapon sounds that might serve for griffons. Soldiers can be served by Bugbear Battle, or there’s also Menador Keep. That set has a lot of good soldier moods, along with wyvern wings, and erinyes (winged devils), and a great one-shot called screaming arrow, which sounds like a griffon stooping to attack with a shriek.
Stones Over Sandpoint has a great hurled stone one-shot that might do for a ballista. Wizard Spells - Ezren also has a good crossbow fire one shot that’s deeper, that could work as well.