We have this info from November 2011 from Chef Bob Burdick:
"Hi, in Universal Studios. We have fruit stands in the parks with apples, oranges, grapes, watermelon on them. Also have lemon and strawberry slush carts which will be ok, also have turkey legs on carts that are just smoke plain. We have a full service unit it is Lombard's landing and Finnegans, We have a chef in each unit have the server bring the chef to the table and he can go over all the things he can do for you In Islands of Adventure we have 2 full service units one called Confisco's and one is Mytho's, We have Chefs in both of those units, have server bring Chef to table and he can go over the things he can do for you,. I have another walk up unit it is Thunder Falls, I have smoke chicken, smoke ribs, and roasted corn on cob and roasted potatoes with fresh herbs and salt and pepper, also have French fries all natural cooked in soy blend oil that is the only thing cooked in those fryers too. I will also say no desserts at all from any of the restaurants too.
We also have three broomsticks which have smoked chicken and smoked pork ribs, roasted corn on cob, baked potatoes, roasted potatoes with onions, garlic, salt and pepper, and fresh herbs and some salads too.
The butterbeer will be ok."
Our sons' allergies are to eggs, tree nuts, peanuts, mushrooms and most legumes (they can eat soy). A lady named Pam helped us with ordering at the Three Broomsticks (we ate here 3 times!), and it was a great experience! I wouldn't go on this info alone, especially after many months, but it gives good starting points for where to look for allergy safe foods while at Universal.