Add the scallions, onion, garlic, Scotch bonnet peppers, fresh thyme, ground allspice, cinnamon, nutmeg, black pepper, salt, brown sugar, soy sauce, lime juice, white vinegar, and oil to a blender. Blend until a smooth, thick paste forms.
Coat the chicken leg quarters generously with the jerk marinade, making sure every piece is well covered. Cover and refrigerate for at least 2 hours, although marinating overnight will give the chicken the best flavor.
Preheat the air fryer to 190°C (375°F) if required. Arrange the chicken in a single layer, leaving space between each piece. Air fry for 30–40 minutes, flipping the chicken halfway through cooking so it cooks evenly on both sides.
During the last 5 minutes of cooking, brush the chicken with a little extra jerk marinade or reserved sauce. Increase the air fryer temperature to 200°C (400°F) and continue cooking until the chicken develops a beautifully glossy, caramelized finish and reaches an internal temperature of 74°C (165°F).
While the chicken cooks, combine the diced mangoes, red onion, red bell pepper, lime juice, chopped cilantro, and a pinch of salt in a bowl. Toss gently until everything is evenly mixed, then refrigerate until ready to serve.
In a small bowl, stir together the Greek yogurt, thick coconut milk, lime zest, lime juice, and a pinch of salt until smooth and creamy.
Plate the hot jerk chicken alongside a generous spoonful of mango salsa. Finish with a drizzle of the coconut-lime crema and serve immediately.