Hi Suu and welcome.
I had the 7/12 nerve graft about 2 1/2 years ago. I'm not sure if it's done differently there than it is here in the states, but my tongue, while a little numb, moves just fine! Ask anyone who has had to listen to me talk...and talk....and talk....
Immediately post op, it was a little hard to get used to and my speech was not very good, but it's fine now. I do have diminished sensation on that side of my tongue and can't taste things quite like I used to, but the other side is fine and seems to have really picked up the slack for the AN side. I had little to no movement before the graft and my face was very droopy on that side. I still don't have my big smile back, but my face is symmetrical now and I can do a closed mouth smile, which I am happy with. At least it's better than it was! I would talk to your specialist about it because I think that ENT is just passing along what he's heard about the procedure and doesn't really know a lot about it.
It's still early in your recovery, so you have time to do some research. In the mean time, hang onto that kidney...you might need it for something else!
Good luck!
Lori