Preheat oven to 400°F (200°C). Toss squash, Brussels sprouts, and onion with olive oil, salt, and pepper. Roast for about 20–25 minutes until tender with lightly crisped edges.
Bring salted water or broth to a boil and cook couscous according to package directions. Drain excess water if needed and let it cool slightly to prevent sogginess.
Whisk olive oil, lemon juice, maple syrup, mustard, salt, and pepper until smooth. Taste and adjust acidity or sweetness to your liking before combining with salad.
In a large bowl, mix couscous with roasted vegetables, cranberries, nuts, and herbs. Gently fold everything so ingredients stay intact and evenly distributed.
Sprinkle feta and pomegranate seeds over the top before serving. Serve warm or chilled, depending on preference and occasion.