Is there any substitute for the vegan butter/regular by …

Name: Cherry Apple Galette
Prep time: 30 min
Cook time: 45 min
Total time: 1 h 15 min
Yield: 6
Cuisine: Gluten-Free
Ingredients: 1/2 cup GF buckwheat flour (fine and light in colour); 1 cup GF oat flour (I milled quick oats); 1/2 cup tapioca flour; 1/2 cup cold butter (vegan or regular), cubbed; 1/2 teaspoon sea salt; 1 tablespoon coconut palm sugar; 5 tablespoons water, ice cold; 2 generous cups frozen cherries; 3 apples, peeled/diced; 1/3 cup maple syrup; 1 teaspoon vanilla extract (or 1/4 teaspoon pure vanilla bean powder); 2-3 tablespoons GF minute tapioca or 1.5 tablespoons tapioca flour; Turbinado sugar or organic cane sugar (optional)