To prepare blueberry filling: Combine 2 cups blueberries, water and sugar in a saucepan. Bring to a boil over medium heat. Cook, stirring, until the berries soften into a sauce, 3 to 5 minutes. Remove from heat; stir in remaining 2 cups blueberries and vanilla. Set aside.
To prepare & assemble shortcakes: Preheat oven to 425 °F. Coat a baking sheet with cooking spray.
Whisk flour, cornmeal, 1/4 cup sugar, baking powder, baking soda and salt in a mixing bowl. Using a pastry blender or your fingers, cut cream cheese into the dry ingredients until the mixture resembles coarse meal. Combine 3/4 cup buttermilk, oil and vanilla in a glass measuring cup. Make a well in the dry ingredients. Add the wet ingredients and stir with a fork until just combined. (The dough will be slightly sticky; do not overmix.)
Turn the dough out onto a lightly floured surface. Gently pat into a 3/4-inch-thick circle. With a floured knife, cut dough into 8 triangles; place on the prepared baking sheet.
Combine pecans and the remaining 1 tablespoon sugar in a small bowl. Brush shortcake tops with the remaining 2 tablespoons buttermilk and sprinkle with the pecan mixture.
Bake the shortcakes until golden, 10 to 12 minutes. Transfer to a wire rack to cool slightly. To serve, split shortcakes in half with a serrated knife. Set the bottoms on dessert plates. Spoon on blueberry filling and lemon curd. Set the tops on at an angle. Serve immediately.
Make Ahead Tip: Cover and refrigerate the blueberry filling (Step 2) for up to 1 day.