Whisk together flour, paprika, salt, and water in a large bowl until smooth with no lumps.
In a separate small bowl, mix the cornstarch with garlic powder and onion powder.
Toss the cauliflower florets in the flour batter until completely coated.
Sprinkle the cornstarch mixture over the coated florets and toss again to coat evenly.
Preheat the air fryer to 400°F for 3 minutes.
Arrange the cauliflower in a single layer in the air fryer basket with space between pieces. Cook in batches if needed.
Cook for 12 minutes, shaking the basket halfway through at the 6-minute mark.
Remove the basket and brush each floret with buffalo sauce using a pastry brush.
Return to the air fryer and cook for 3 more minutes until the sauce sets and edges are crispy.
Serve immediately with vegan ranch (optional) and celery sticks if desired.