Beat confectioners' sugar, butter, and 1 tablespoon apple juice concentrate together in a bowl using an electric mixer until light and fluffy; stir in flour and salt until dough is just combined. Roll dough into 3/4-inch balls and arrange on ungreased baking sheets.
Bake in the preheated oven until edges are light golden brown, 12 to 17 minutes. Immediately insert toothpicks in the center of each cookie. Place cookies on a wire rack to cool completely.
Combine caramels, 2 tablespoons apple juice concentrate, and water in a saucepan over low heat; cook and stir until mixture is smooth, 5 to 10 minutes. Spoon caramel sauce over each cookie, letting excess caramel sauce drip off.
Pour walnuts onto a plate. Press the bottom of each caramel-coated cookie into the walnuts and transfer to a sheet of waxed paper to set.