I can't say that I've ever seen a realignment of a duck bill, though I remember seeing some progress made on a chicken cross-beak. He will likely learn how to eat anyway. I'm just not sure what issues the cross could cause long-term. They are so highly adaptive and amazing though!
Wow, that's quite extreme cross beak. I also have a duck that hatched with both sides missing, but alignment isn't too bad. He's almost a year old now!
I'm honestly not sure about the tuna, chicken, etc. (maybe the cause of the smelly gas?) I would suggest trying some chick starter...