Combine mango, 1/2 cup sugar, lemon juice, and salt in a food processor; puree until smooth. Add egg yolks; process for 15 seconds.
Pour mango mixture through a sieve set over a large metal bowl, pressing on solids with the back of a spatula to release as much puree as possible. Discard solids in sieve.
Fill a large saucepan with 2 inches of water; bring to a simmer. Set metal bowl on top; whisk puree until thickened and an instant-read thermometer inserted into the center registers 170 degrees F (77 degrees C), about 10 minutes.
Place metal bowl on a towel on a flat work surface. Whisk in butter 1 piece at a time until blended. Cover with plastic wrap and refrigerate, 8 hours to overnight.
Combine milk and coconut pudding mix in a saucepan. Bring to boil, stirring constantly until thickened. Remove from heat; fold in grated coconut and vanilla extract. Refrigerate until set, about 1 hour.
Beat heavy cream in a chilled glass or metal bowl with an electric mixer until soft peaks form. Add 1/4 cup sugar gradually, continuing to beat until stiff peaks form.
Place 1/2 of the pound cake cubes in the bottom of a large trifle bowl. Layer some of the bananas, pineapple, and strawberries on top. Spoon 1/2 of the mango puree and coconut pudding on top. Repeat layers with remaining pound cake, bananas, pineapple, strawberries, mango puree, and coconut pudding.
Spoon whipped cream on top in big, fluffy swirls. Chill until serving.
