Preheat the oven to 350 degrees F (175 degrees C). Heat butter in a large pot over medium-high heat. Saute celery, onion, and apple in the hot butter until softened, 5 to 7 minutes. Stir in sage, thyme, paprika, salt, and pepper. Add chicken broth, brown sugar, and maple syrup; stir to combine and reduce slightly, 3 to 4 minutes. Add waffles and toss until softened, 3 to 4 minutes. Stir in pecans and buttermilk; toss until completely coated. Stir in eggs to bind everything together. Spoon stuffing into a large casserole dish. Bake in the preheated oven until browned, about 45 minutes. Remove from the oven and let stand for 5 minutes before serving.