Place chicken and oil in a large bowl; toss to coat. Combine 1/2 teaspoon salt, 1/4 teaspoon cumin, and paprika in a bowl. Add spice mixture to chicken mixture; toss to coat. Combine remaining 1/4 teaspoon salt, remaining 1/4 teaspoon cumin, yogurt, lemon juice, tahini, and garlic in a small bowl. Set aside. Heat farro according to package directions. Place 1/2 cup farro in each of 4 bowls. Top each serving with about 3/4 cup chicken mixture, 1/2 cup cucumber, 1/2 cup tomatoes, about 1/3 cup chickpeas, and 2 1/2 tablespoons Greek yogurt mixture. Top with parsley and black pepper.