Spray four 10x20-inch sheets of parchment paper with cooking spray.
Mix cooked rice, file powder, 1 1/2 teaspoons Cajun seasoning, 1/2 teaspoon garlic powder, and 1/2 teaspoon cumin in a bowl. Divide rice mixture evenly over prepared parchment paper.
Toss tomatoes, red bell pepper, green bell pepper, green onion, and okra in a large bowl with 1 1/2 teaspoon Cajun seasoning until well coated. Divide vegetable mixture evenly over rice.
Combine crawfish, shrimp, andouille sausage, remaining 1 1/2 teaspoons Cajun seasoning, 1/2 teaspoon garlic powder, and 1/2 teaspoon cumin in another bowl. Divide seafood mixture evenly over vegetables. Pour about 1 tablespoon chicken broth over seafood mixture and top each portion with 4 clams.
Fold parchment paper around seafood mixture, sealing edges to form a pouch. Place the pouches on a microwave-safe platter.
Heat pouches in microwave on high until shrimp are bright pink on the outside and the meat is no longer transparent in the center, about 4 minutes.