In a 3-1/2- or 4-quart slow cooker layer onion, chicken, red pepper, yellow pepper, currants, and garlic. In a large bowl combine tomatoes, tapioca, curry powder, salt, cumin, and mace. Pour over mixture in cooker.
Cover and cook on low-heat setting for 5 to 6 hours or on high-heat setting for 2-1/2 to 3 hours.
Stir parsley into hot cooked rice. Serve chicken mixture in shallow bowls over rice. Sprinkle with green onion and almonds.