I'm glad to see that you're feeling a bit more optimisitic.
We all understand how upsetting it can be when our favorite little critters have any problems.
Most of your care is the way it should be but there are just a few things that could be changed to improve his health.
The forum moderators, who are longterm chamkeepers and at least one chamkeeping veterinarian, recently added some caresheets and they contain a great deal of valuable information.
Most importantly, they outline the differences in care for chams of different ages.
Here is the Veiled caresheet:
https://www.chameleonforums.com/care/caresheets/veiled/
For a 5 month old Veiled, the basking area should be a bit cooler--about 85 degrees.
The easiest way to do this is to use a lower wattage regular household bulb--you don't need an expensive "special" basking bulb that petstores sell.
I would suggest that you gutload the feeders with fresh veggies and fruits to know that your cham is really getting good nutrients from his food.
Commercial gutloads can be pretty poor nutritionwise.
This page, also done by the moderators, offers ideas for an easy to make gutload:
https://www.chameleonforums.com/care/food/
In the wild chams eat dozens of different kinds of insects --a menu that varies by the day and by the season.
Different insects contain more of or less of different vitamins, minerals, etc and it is the fact that they eat different kinds which keeps them healthy.
For this reason, the more varieties of feeders you can give your cham, the better it is for him.
Silkworms,hornworms, Phoenixworms,Dubias, Blue Bottle flies, Isopods are all good additions to the diet and even superworms or waxworms can be used once in a while as treat.
I didn't see any multivitamin powder in your supplements.
Lightly dusting feeders 2x a month can help to ensure that he doesn't develop any deficiencies.
FWIW, I use Reptivite without D3. A few of the forum sponsors carry it, as well as Amazon and local stores.
Lastly, you can add a cham safe live plant to help keep the humidity up, but 50% is within the range of what is needed.
On days that are warm enough, you can bring him outside for some supervised outdoor time.
I hope your cham is well soon and that you've found this to be helpful.
We're all rooting for you and your cham!