In a bowl, combine cracker crumbs, 2 tablespoons sugar, salt and 1/2 cup butter; reserve 1/2 cup. Press the remaining crumbs into an ungreased 9-in. square baking pan. Chill. Meanwhile, cook pudding according to package directions; cool for 5 minutes. Spread over crust. Chill.
In a saucepan over medium heat, cook cranberries, raisins and water until berries pop, about 5-10 minutes. Stir in remaining sugar. Combine cornstarch and cold water until smooth; add to the cranberry mixture. Bring to a boil; cook and stir for 2 minutes. Remove from the heat; stir in remaining butter. Cool to room temperature.
Spread cranberry mixture over pudding layer. Prepare whipped topping according to package directions; spread over cranberry layer. Sprinkle with reserved crumbs. Chill for at least 6 hours. Store in the refrigerator.