In a large bowl, whisk together the buttermilk, 1 tablespoon of the salt, 1 teaspoon of the paprika, ½ teaspoon of the white pepper, and ½ teaspoon of the garlic powder. Add the chicken, making sure it is fully submerged. Cover and refrigerate for at least 4 hours, or overnight.
In a separate large bowl, whisk together the flour, cornstarch, remaining 1 tablespoon + 2 teaspoons paprika, remaining 2 teaspoons salt, remaining 1 teaspoon white pepper, remaining 1 teaspoon garlic powder, black pepper, onion powder, thyme, basil, oregano, ground mustard, celery salt, and ground ginger.
Remove the chicken from the buttermilk and dredge each piece thoroughly in the seasoned flour mixture, pressing firmly so the coating adheres well. Place coated chicken on a rack and let rest for 10–15 minutes.
Preheat the air fryer to 390°F. Spray the basket generously with oil.
Arrange the chicken in a single layer in the basket. Spray the tops generously with oil until no dry flour spots remain.
Cook for 12 minutes. Flip the chicken, spray again with oil, and cook an additional 10–16 minutes, or until the coating is deep golden brown and the internal temperature reaches 175–185°F