Preheat oven to 450°F with oven rack positioned 8 inches from heat source. Place chicken and sweet potatoes on a rimmed baking sheet. Drizzle with oil; toss to coat, and spread evenly on pan with chicken facing skin side up. Sprinkle evenly with pepper, cumin, and 1/2 teaspoon of the salt. Sprinkle olives over baking sheet; add lemon wedges.
Roast in preheated oven until a thermometer inserted in thickest portion of chicken registers 165°F and potatoes are almost tender, about 30 minutes. Increase oven temperature to broil (do not remove baking sheet); broil until chicken is browned, 5 to 7 minutes. Remove from oven; sprinkle with tomato, raisins, mint, and remaining 1/4 teaspoon salt. Squeeze juice from lemon wedges over top, and serve.