In a slow cooker, combine tomatoes, all beans, onion, bell pepper, garlic, chili powder, oregano, cumin, coriander, and hot sauce.Cover and cook on low for 6 to 8 hours on on high for 3 to 4 hours.Ten minutes before serving, add couscous, cover, and cook until couscous is tender. Season to taste with salt and pepper.Just before serving, top each serving with shredded cheese and cilantro.