Preheat the oven to 400°F. In a bowl, whisk buffalo sauce, garlic powder, smoked paprika, and black pepper. Toss shredded tofu in the sauce until fully coated. Spread on a parchment-lined baking sheet and bake 25–30 minutes, tossing halfway until crispy at the edges.
While tofu bakes, combine vegan mayo, apple cider vinegar, lemon juice, Dijon mustard, and maple syrup in a large bowl. Add celery, cabbage, red onion, and carrot. Toss until coated, season with salt and pepper, and refrigerate until ready to use.
Lower oven temperature to 375°F. Slice dinner rolls in half, keeping the bottoms intact, and arrange in a greased baking dish. Spread ranch on the bottom buns, add half the cheese, layer baked buffalo tofu, sprinkle remaining cheese, and drizzle more ranch or buffalo sauce. Place top buns on.
Cover sliders loosely with foil and bake for 12–15 minutes until the cheese melts. Remove foil and brush tops with melted vegan butter mixed with garlic and parsley. Bake uncovered for 5–7 minutes until golden brown.
Let the sliders cool slightly. Lift tops and add celery slaw or serve on the side. Replace tops and serve immediately with extra ranch or buffalo sauce for dipping.