Combine 2 1/2 cups water, rice, currants or raisins and 1/4 tsp salt in a medium saucepan. Bring to a boil, reduce heat, cover and simmer about 45 minutes, until water is absorbed. Shut off heat, let stand covered 10 minutes, and fluff with a fork. Transfer mixture to a large bowl, and cool completely.
Pre-heat oven to 350 degrees. Spread walnuts on cookie sheet, roast 6-8 minutes, cool and finely chop. Pile the dill, parsley, and scallions onto a cutting board, and finely chop.
Cut off top of each pepper, and reserve the top. Discard seeds and white membranes. Put turkey in a large bowl, add 1 cup mozzarella, 1/4 cup feta, the rice mixture, walnuts, and all but 2 tablespoons of the chopped herbs. Add garlic, lemon juice, lemon zest, 1 1/2 tsp. salt and 1/2 tsp. pepper. Gently mix with your hands, stuff each pepper, and cover with top of pepper.
Make sauce: whisk 3 cups water, tomatoe puree, brown sugar, olive oil, and cinnamon stick in a wide, deep, saucepan. Arrange stuffed peppers upright in sauce. Cover, and simmer over medium-low heat for 1 hour.
Pre-heat broiler, carefully remove peppers to baking dish, remove tops, sprinkle reserved herbs, mozzarella and feta cheese over the filling, and broil until melted, 2 minutes. Replace tops, serve peppers in a shallow bowl with sauce.