Whisk flour and confectioners' sugar together in a mixing bowl. Cut in the butter with a knife or pastry blender until the mixture resembles coarse crumbs. Pat flour-butter mixture into the bottom of a small rimmed baking sheet.
Bake in the preheated oven until golden, 8 to 10 minutes. Cool completely.
Beat cream cheese, 1/2 cup white sugar, and vanilla together in a bowl until smooth and creamy; spread over cooled crust.
Arrange bananas, mandarin oranges, strawberries, and grapes on top of the cream cheese spread.
Add enough water to reserved mandarin orange juice to equal 1 cup liquid. Whisk orange liquid, 1/2 cup white sugar, cornstarch, and lemon juice together in a saucepan; boil, whisking constantly, until thickened, about 1 minute. Drizzle glaze over fruit. Refrigerate until cold, at least 1 hour.