Yes, there is a very unique mix of ingredients going into this recipe to create a balance of flavors. Buttermilk and cream cheese frosting are both adding tangy flavors that help to even out the flavors of sweetness in the cake, while pineapple helps to cut some of the sweetness with acidity. Buttermilk also creates a chemical reaction in the baking process that aids in creating the moist and tender texture of the cake. All of them are balanced intentionally, so any substitutions here would throw the flavors off balance. If you want to edit the ingredients please try it as written the first time. The only substitute I'd make is listed next.