Thats a very good result a major change. I think that another session of about 2-2,5 k grafts would complete it. But you could also just let it be as it is. I think its age appropriate.
Sry i misread some of your post. If you left 23 cm2 untouched and the density to give an illusion of a full head of hair is 35 per square cm2 Then you will need 805 grafts for that area. Then you will have to add 5-15 grafts at all the cm2 where you had transplanted 20-30 per square cm2. I dont know how much that is ? And then plus with 10 % because some of the grafts will not survive.
Another solution is to just add 1 thousand grafts to the crown area. I actually think that would make a big difference as well.
Im not sure whether i would suggest another operation or not. I only gave my input on this because we have talked about it via email.