Essentially, if you look at the normal menu you can get the non-allergy version of anything on the menu.
They will have alternate sauces, if you aren't comfortable with the buffet line they will make something separate and bring it out for you. It's not something you have to worry about, note the allergy on your reservation and speak to the chef when you arrive. They will walk you through it.
Akershus is really the only place we haven't gone back to since my son's allergies, but really because we go for breakfast and we loved their breakfast menu but it is completely based on my son's allergens. (when you are allergic to wheat, soy, egg, nuts and dairy you get the same breakfast everywhere, no matter how much you pay, so we save and eat CS breakfasts.