Make couscous: Bring water, orange juice, and lemon juice to a boil in a medium saucepan. Stir in couscous, cover, and simmer for 20 minutes. Cover a large rimmed baking sheet with parchment paper. Spread couscous out on a pan to cool slightly.

Make salad: In a medium saucepan, whisk together orange juice, olive oil, and vinegar. Bring to a light simmer. Add dried cherries and remove from heat. Let mixture set for 5 minutes. Drain off liquid into another bowl and reserve.

While still slightly warm to the touch, slide couscous off parchment paper into a large bowl. Whisk reserved cherry liquid and add couscous. Stir in cherries, celery, arugula, walnuts, and shallots. Salt and pepper to taste. Toss salad and serve warm or at room temperature, topped with very thin shavings of cheese.