Place a mesh strainer over a medium bowl and drain the pineapple chunks and crushed pineapple. Squeeze or press to remove as much moisture as possible Transfer the drained pineapple solids to a large bowl. Set the bowls of pineapple and pineapple juice aside.
Combine the granulated sugar and flour in a medium saucepan; whisk until well combined. Whisk in 1 cup of the reserved pineapple juice, the egg, and salt. Place the pan over medium heat and cook until thickened, whisking constantly, about 4 to 6 minutes. The mixture should coat the back of a spoon.
Place a mesh strainer over a large bowl, then pour the custard through it; stir in the lemon juice. Cover the bowl and refrigerate the custard for about 30 minutes or until chilled.
While the custard is chilling, cook the pasta. Fill a medium saucepan with water and bring it to a boil over high heat. Add the pasta, then reduce the heat to medium-low. Cook as directed on the package or until tender, about 6 to 10 minutes, depending on the brand. Do a taste test to ensure it is tender, not al dente. Pour the pasta into a colander and run cold water over it to cool completely. Set the pasta aside to drain thoroughly.
To prepare the whipped cream, beat the heavy cream in a medium bowl with an electric mixer until frothy. Gradually beat in the confectioners' sugar until stiff peaks form. You will have about 4 cups of whipped cream. Reserve 1 cup of whipped cream for the topping and refrigerate it until ready to serve.
Remove the chilled, set custard from the refrigerator, then add the cold drained pasta; stir to coat.
Add the well-drained pineapple, mandarin orange sections, coconut, and miniature marshmallows. Stir gently to combine, then fold in the whipped cream. Transfer the frog eye salad to a serving bowl.
Serve frog eye salad on the side with a meal or in dessert bowls or cups with reserved whipped cream, maraschino cherries, and toasted coconut.