Preheat air fryer to 325°. Combine walnuts, sugar and cinnamon., Place 1 sheet of phyllo dough on a 15x12-in. piece of waxed paper; brush with butter. Place a second phyllo sheet on top, brushing it with butter. (Keep remaining phyllo covered with a damp towel to prevent it from drying out.) Sprinkle with 1/4 cup walnut mixture. Using waxed paper, roll up tightly jelly-roll style, starting with a long side, removing paper as you roll. Slice roll into 4 smaller rolls. Brush with butter; secure with toothpicks. Repeat with remaining phyllo dough and 1/4 cups of walnut mixture. In batches, place in a single layer on greased tray in air-fryer basket. Cook until light brown, 9-11 minutes. Cool on a wire rack. Discard toothpicks., Meanwhile, in a small saucepan, combine all syrup ingredients. Bring to a boil. Reduce heat; simmer 5 minutes. Cool 10 minutes. Transfer cinnamon rolls to a serving platter; drizzle with syrup. Sprinkle with remaining walnut mixture.