Bring 2½ cups water to a boil in a medium saucepan. Stir in the couscous, remove from heat, and cover. Let sit until the couscous is tender and ¾ of the water is absorbed, about 5 minutes. Stir in the cream cheese and Parmesan until melted, then season with salt and pepper. Keep the pot covered while you cook the shrimp.
Season the shrimp with the paprika, ½ teaspoon salt, and ¼ teaspoon pepper. Heat the oil in a large skillet over medium-high heat until nearly smoking. Add the shrimp in a single layer and cook, turning once halfway through, until the paprika is browned and the shrimp are cooked through, about 3 minutes. Turn off heat, add half the scallions, and toss to combine. Stir in the lemon juice.
Serve the shrimp over the couscous and garnish with the remaining scallions.