Melt 4 tablespoons butter in a large skillet over medium heat. Add the brown sugar and stir until dissolved. Add the pineapple rings in batches to avoid over-crowding and cook until caramelized on each side, about 3 minutes.
Combine the flour, baking powder, baking soda, and salt in a large mixing bowl. In another bowl, combine the buttermilk, sugar, melted butter, and vanilla. Add the wet ingredients to the dry ingredients and mix.
Heat a griddle or skillet over medium heat. Spray with cooking spray. Pour 1/3 cup of batter per pancake onto the griddle. Add 1 pineapple slice and 1 cherry per pancake. Cook until bubbles start to form on top of the pancakes and the bottom is golden brown, about 3 minutes. Flip the pancakes over and cook until golden brown, about 3 minutes. Transfer pancakes to a plate and keep warm in the oven while you make the rest.
Combine the cherry juice with the maple syrup and serve with the pancakes.