To make the berry filling: In a large saucepan bring the 4 cups of raspberry-cranberry juice to a boil over high heat.
Cook until reduced to about 1 1/2 cups, about 10 minutes.
In a small bowl, stir together 4 tablespoons Cointreau with the cornstarch.
Whisk into the reduced raspberry-cranberry juice and cook on medium heat until juice has thickened and become clear.
Remove from the heat and add the two 16-ounce bags of frozen raspberries.
Set aside and let stand until the berries have thawed.
To make the mousse layer: In a heavy nonreactive saucepan (stainless steel or enamel) combine the egg yolks, sugar, orange juice and butter.
Cook over medium heat, stirring to dissolve the sugar, until the butter melts.
Reduce the heat to medium-low and stir constantly with a wooden spoon until the mixture thickly coats the back of the spoon, about 5 to 10 minutes.
Strain mousse through a fine-mesh strainer to remove lumps, into a large bowl.
The orange mousse mixture will be very thick.
Refrigerate, covered with plastic wrap on the surface to prevent a skin from forming, until completely chilled, about half an hour.
When mixture is chilled, in a large bowl, mash mascarpone cheese with a rubber spatula, add 1/4 cup of the orange mousse and stir until smooth and creamy.
Stir in the remaining orange mousse and then fold in the whipped cream.
To make the soaking liquid: In a small bowl, mix the 1 cup of thawed raspberry-cranberry concentrate with 2 tablespoons of Cointreau.
Stir until blended and set aside.
To assemble the Trifle:
In a 12-cup trifle bowl or a glass bowl with straight sides, layer half the slices of the angel-food cake on the bottom, making sure that only the white, cut edges of the cake are visible against the sides of the trifle bowl.
Drizzle cake with half the soaking liquid.
Evenly spread half the orange mousse mixture over the soaked cake slices.
Spread three-quarters of the berry filling carefully over the mousse.
Layer the remaining angel-food cake slices on top of berry filling, cut sides against the glass.
Drizzle cake with remaining soaking liquid.
Spread remaining orange mousse mixture over cake.
Mound remaining quarter of the raspberry mixture on top of the mousse in the center of the bowl.
Pipe whipped cream on top of trifle to decorate.
Garnish with fresh raspberries.
Refrigerate for 4 to 6 hours or overnight before serving.