Combine vanilla wafer crumbs, 1 cup coconut, and melted butter in a medium bowl. Mix until evenly moistened; press into the bottom and up sides of a 9-inch springform pan. Chill.

Pour pineapple juice into a small saucepan; sprinkle gelatin over juice and let stand until gelatin softened, 5 minutes. Cook and stir over medium heat until gelatin dissolved. Remove from heat; set aside.

Beat cream cheese and 3/4 cup sugar with an electric mixer in a large bowl until smooth. Beat in gelatin mixture until well blended. Beat in rum and coconut extract until smooth and blended; gently fold in whipped topping. Spoon into the prepared crust. Chill until set, 6 hours or overnight.

Combine undrained pineapple, 2 tablespoons sugar, and cornstarch in a small saucepan over medium heat; cook and stir until mixture boils and slightly thickens. Chill. Spoon pineapple mixture over top of cheesecake before serving. Garnish with remaining 1 teaspoon coconut.