Puree cumin, coriander, peppercorn and cardamom in a blender until very fine. Add parsley, mint, oregano, garlic, fresno, salt, vinegar and ¼ cup oil and puree until a thick pesto like paste forms. Place chicken in a large resealable plastic bag and pour in marinade. Seal bag, pressing out any air. Chill at least 3 hours and up to 24.
Prepare a grill for medium-high, indirect heat (for a charcoal grill, bank coals on one side of grill; for a gas grill, leave one or two burners off). Thoroughly clean grates and brush with oil. Set chickens, skin side up, on grate over indirect heat. Cover grill, placing cover vent (if your grill has one) over chickens so it draws heat up and over them. Grill, rotating chickens as needed so that they color evenly, until skins are lightly browned, 15–20 minutes.
Turn chickens and continue to cook, covered, until skins are deep golden brown and crisp and an instant-read thermometer inserted into the thickest part of breasts registers 160°, 20–25 minutes. Transfer chickens to a cutting board and let rest at least 10 minutes before carving.
Mix olives, lemon juice, chopped parsley, remaining ¼ cup oil, and any accumulated juices from chicken on the cutting board in a medium bowl. Season with salt.
To serve, arrange carved chickens on a platter and top with olive mixture and parsley leaves.