Preheat oven to 350°F (175°C). Line a 12-cup muffin tin with paper liners.

Whisk together cake flour, baking powder, baking soda, and salt in a bowl.

In a stand mixer, cream butter and sugar until pale and fluffy (about 3-5 minutes).

Add eggs one at a time, mixing well. Mix in vanilla and coconut extracts.

Alternately add the dry ingredients and buttermilk in three batches, mixing on low speed until just combined.

Fill cupcake liners 2/3 full. Bake for 18-20 minutes until a toothpick comes out clean. Let cool completely.

For the curd: Whisk sugar, lemon juice, pineapple puree, zest, and egg yolks in a heatproof bowl. Place over simmering water.

Whisk constantly for 8-10 minutes until thickened. Strain through a fine-mesh sieve, then whisk in cold butter until glossy. Chill for 2 hours.

For the buttercream: Beat butter until creamy, add powdered sugar, cream, and vanilla. Beat until stiff.

Color small amounts of frosting yellow and green. Tint half the remaining frosting pink, leave the rest white.

Using a piping bag striped with pink color and fitted with a petal tip, pipe 5-petal hibiscus flowers on parchment squares. Add yellow stamens and green tips. Freeze until solid.

To assemble: Spoon a pool of chilled curd onto each cupcake. Peel frozen flowers off parchment and place on top of the curd. Serve once flowers come to room temperature.