Place chicken into a large pot and add water to cover. Bring to a boil over high heat, then reduce the heat to medium-low, cover, and simmer until chicken is no longer pink and the juices run clear, about 10 minutes.

Remove from the pot and let sit until cool enough to handle, 5 to 10 minutes. Shred chicken with two forks.

Combine sour cream, condensed soup, and chili powder in a saucepan. Bring to a simmer, stirring occasionally, then turn off the heat and cover to keep warm.

At the same time, melt butter in a skillet over medium heat. Add onion; cook and stir until translucent, about 5 minutes. Add shredded chicken, water, 1/2 of the green onions, green chiles, and taco seasoning; simmer for 10 minutes. Stir in lime juice, onion powder, and garlic powder; simmer for 10 more minutes.

Preheat the oven to 350 degrees F (175 degrees C).

Stir 1 cup soup mixture into the skillet with the chicken. Spread remaining soup mixture over the bottom of a 9x13-inch baking dish.

Fill each tortilla with 1/5 of the chicken mixture and about 5 tablespoons Cheddar cheese.

Roll tortillas around filling and place enchiladas, seam-side down, into the baking dish. Pour enchilada sauce over top and sprinkle with remaining Cheddar, remaining green onions, and olives.