I would definitely see a dietician. Because your kiddo is still growing and CDED is a restrictive diet and Orgain is not considered complete nutrition. I would consider other formulas - Peptamen and Pediasure Peptide are commonly used semi-elemental formulas. They're partially broken down so easier for the gut to absorb. Your GI may have access to samples, so your son can try different flavors before you order one. I will say that semi-elemental formulas are not the most palatable - not like Ensure or Boost. But kids can and do get used to them - even teens. My daughter started out hating Peptamen Jr. but over time, she actually got so used to the taste that she missed it when she moved to tube feeds!
(She moved to tube feeds because she simply could not drink enough formula to maintain her weight, much less gain. And once she did, she found them SO much easier than trying to drink formula that she said she would never go back!).
Tube feeds are another good option for kids who can't drink enough formula or hate the taste of semi-elemental formula. It honestly sounds much more intimidating than it is. My daughter used an NG (naso-gastric) tube - she inserted the tube at night, did feeds overnight and pulled it out in the morning, so no one at school had to know.
I really, REALLY doubt this is allowed with CDED, but you can also get unflavored or vanilla Peptamen Jr. and add chocolate or strawberry syrup or honey. I've even heard of maple syrup being used. But you could also blend in a banana or strawberries and see what that tastes like.
If you want to avoid Ensure and Boost, semi-elemental formulas are generally considered the next option and they often do not contain all the ingredients Ensure and Boost do (such as no carrageenan for example). But there is also a plant-based version of Ensure that is newer. Kate Farms Peptide is another semi-elemental formula that is plant based (but my daughter has never tried that, so I have no idea how that tastes).
Good luck!!