Soak the currants in the amaretto at least 30 minutes and up to 1 day. Strain and set aside; reserve the amaretto. Beat the butter, 2 cups all-purpose flour, the almond flour, granulated sugar, milk powder, salt and egg in a large bowl with a mixer on low speed until combined but not fluffy, about 1 minute. Mix in the currants and candied citron.
Toss the candied cherries with the remaining 2 tablespoons all-purpose flour. Stir into the dough using a wooden spoon. Divide the dough in half and roll each half into a 12-inch-long log. Wrap tightly in plastic wrap and freeze until firm, about 5 hours.
Position racks in the upper and lower thirds of the oven; preheat to 350 degrees F. Line 2 baking sheets with parchment paper. Slice the frozen dough into 1/2-inch-thick rounds. Arrange the slices 1 inch apart on the prepared pans.
Bake, switching the pans halfway through, until the cookies are firm and light golden around the edges, 20 to 25 minutes. Let cool 5 minutes on the pans, then brush the tops and sides of each cookie with the reserved amaretto. Transfer to a rack to cool completely. Roll the edges of each cookie in the confectioners' sugar.