1. Prepare citrus: Cut top and bottom off one orange. Set it on end. Using a large, sharp knife, slice off the peel, pith, and thin membrane enclosing the fruit, from top to bottom. Remove segments: Reserve juice. Repeat with remaining citrus. Combine fruit juices, adding enough orange juice to total 2 cups.
2. Prepare gelatin: In a small pot, heat 1 1/2 cups juice to a bare simmer. Meanwhile, sprinkle gelatin over remaining juice; allow to soften 2 minutes. Pour simmering juice over gelatin mixture; whisk to dissolve. Refrigerate to cool slightly.
3. Heat oven to 250°F. Cut cake into 1 1/2-inch slices; spread on a baking sheet. Toast until dry, turning once (20 minutes total). Cool.
4. Begin trifle: Cover the bottom of a glass bowl with cake slices (cutting pieces to fit). Sprinkle with Amaretto and orange liqueur. Layer orange segments over cake. Pour in gelatin mixture; cover bowl with plastic wrap. Refrigerate until gelatin is completely set (8 hours to overnight).
5. Pour custard over trifle. Before serving, beat cream until soft peaks form. Add honey and almond extract; continue beating just until cream holds a shape. Fold in yogurt. Dollop onto trifle. Serve.