So sorry you're dealing with this, Fasa's mama.
We just got our first cat about a year ago--a stray that jumped into my arms and ended up staying--so I don't pretend to be an expert. But I'd ask myself how he was feeling otherwise. Does he seem uncomfortable or overly lethargic? He's still coming out to use the litterbox, you said, and although not a big fan of the feeding tube, he's tolerating the feedings?
If he seems otherwise comfortable, I think it would be worth a little bit of a wait to see if the feeding works and/or he starts eating better on his own. Does he have a quiet room with a comfy bed and a litter box where he can be away from the children till he's feeling better?
Sometimes, especially after being doped up, it takes them a few days to de-stress from a stay at the vet--that's true of any animal.
Your vet might also be able to give you some insight. Might be worth having a heart-to-heart talk with the vet, even if you have to pay for another office visit.
Best wishes for you and your kitty. I'll keep you in my prayers. And please keep us posted on his progress!
