Preheat a George Foreman® Grill or an outdoor grill for medium-high heat.
Mix ground turkey, onion, panko, 1/4 cup Buffalo wing sauce, parsley, egg, garlic, celery seed, black pepper, cayenne pepper, paprika, and salt together in a large bowl; form into 12 patties.
Grill patties on the grill for 3 minutes, flip and continue grilling until cooked through, about 2 minutes more. An instant-read thermometer inserted into the center should read at least 165 degrees F (74 degrees C).
Top each burger with a slice of Monterey Jack cheese and place each inside a bun.
Mix ranch dressing and 6 tablespoons Buffalo wing sauce together in a bowl; spread onto each burger.