In a small saucepan over medium heat, bring the milk, sugar, and cherries to a simmer, then remove from the heat. Add the seeds from the vanilla bean and whisk to combine; cover and steep for 10 minutes.
Place the couscous in a large bowl, then pour milk mixture over the top. Stir in the yogurt until well-combined.
Divide evenly between 4 custard cups, sprinkle with cinnamon, and refrigerate for 1 hour before serving. Serve cold.