Heat 2 tablespoons butter in a medium saucepan over medium heat. Add shallots; cook, stirring occasionally, until tender, about 4 minutes. Add rice and cook, stirring, until toasted, about 1 minute. Add wine and cook, stirring, until absorbed.
Gradually add broth 1 cup at a time, stirring, until rice is just tender, 20 to 25 minutes. (You may not need to use all of broth.) Remove from heat and stir in remaining 2 tablespoons butter and Parmesan. Add sage; season with coarse salt and pepper. Spread risotto in a 9-by-13-inch baking dish. Let cool completely.
Form risotto into 1 1/2-inch balls. Insert a cube of Taleggio in center of each. Place flour, eggs, and panko in three shallow dishes; lightly beat eggs. Dredge each ball with flour, then dip in eggs and coat in panko. Transfer to a parchment-lined baking sheet.
Heat 2 inches oil to 360 degrees in a heavy pot over medium-high heat. Fry balls in batches, turning once, until golden brown, about 3 minutes a batch. Transfer to a paper towel-lined plate. Sprinkle with flaky salt.
Fry small sage leaves in oil until crisp and bright green, about 30 seconds. Top risotto balls with fried sage and serve.