Protein, carbs, fibre and vitamins/minerals - sounds good to me! Do you have them every day Kandinsky? If so, I'd be pretty tired too! I have one of my GC twice a week after school and another one all day on a couple of Fridays per month when they're not at nursery, and that's enough for me.
For my after-school GC I quite often make some pasta with a sauce and grated cheese followed by a yoghurt or something like rice pudding (from a tin - he loves it!) Occasionally if we've had something the night before that he likes, for example chicken and roast veg or shepherd's pie, I'll save a portion and re-heat it, but that is the exception rather than the rule. I always try to do something hot as he has a packed lunch at school.
If his parents are happy and your GC have good appetites with a varied diet at home then they'll be getting all they need to be healthy.