It’s good that you are getting more Critical Care in him and that he is eating some greens.
Most emergency clinics seem to know very little about rabbit care, from what I know about the local clinic and from what I’ve read here in the forums.
Has Velvet shown any indication that he has gas? The signs are pressing their stomachs into the floor, or shifting uncomfortably or twisting and turning. If you suspect that he also has gas, infant simethicone drops are very helpful. The brand I have is Mylicon. You can find it in grocery stores, drug stores, any store that has a baby section. The dosage is 1 ml an hour for 3 hours. The simethicone is completely harmless, with no side effects and just passes out of the body. Don’t force more medicine down him than necessary, but if he shows signs of having gas, the infant simethicone will very likely help.
Keep offering different fresh veggies or hay or pellets to him. Sometimes you can get a rabbit more interested in food if you brush the veggie or piece of hay across his mouth/nose area.