As far as sign language style used at the Khall, or anywhere else for that matter, it is supposed to be the kind the deaf person understands best. That is the professional way to interpret. I have to admit, the best sign language I have ever seen was on the ASL DVD's the society put out for the literature. It is amazingly professionally done.
BTW, translation is from one oral language to another written language or from one language on paper to another on paper. Person to person languag-ing is interpreting.