PREHEAT oven to 350°F. Place 1/2 cup of the coconut and the walnuts in food processor container fitted with steel blade; cover. Process until finely ground; set aside.
MIX matzo meal and potato starch; set aside. Beat egg yolks in large bowl with electric mixer on medium speed until well blended. Gradually add sugar, beating about 5 min. or until thick and light in color. Beat in orange juice and matzo meal mixture until well blended. Gently stir in coconut mixture and orange zest.
BEAT egg whites and salt in another bowl until stiff but not dry. (Do not overbeat.) Gently stir in a small amount of the egg whites into batter; gently stir in remaining egg whites. Divide batter evenly between 2 greased and floured 9-inch round cake pans.
BAKE 25 to 30 min. or until toothpick inserted in center comes out clean. Cool 10 min.; remove from pans. Cool completely on wire racks. Place 1 of the cake layers on serving plate. Spread top with about 1-1/2 cups of the whipped topping; sprinkle with half of the pineapple and 1/4 cup of the remaining coconut. Cover with second cake layer. Frost with remaining whipped topping and sprinkle with remaining 1-1/4 cups coconut. Garnish with remaining pineapple. Refrigerate at least 1 hour. Store leftover cake in refrigerator.