It's a common misconception about AA meetings and other self-help groups like that which may meet in jails or prisons: They are NOT in any way an official function of the jail, prison or institution where they are held. They are held by members of AA (or NA, or whatever-A) and brought into the prison from the outside as a courtesy outreach, and the administration of such meetings is not the prison's responsibility. The AA groups are supported only by their own voluntary contributions. AA meetings typically function with very little or no funds, especially those operating inside a prison, so hiring an interpreter is extraoridinarily cost prohibitive. A terp is likely at least $45.00 an hour and an AA meeting may not take in that much in two weeks or a month.
That said, those programs of the prison that are official ought adhere to all reasonable ADA accomodations. I am sure some allowances exist - like maybe they don't have a 24/7 terp for a prison with only a few deaf people, but when it counts, especially in a court setting, they need to have terps. They have to do the same for primarily Spanish speaking prisoners - I see this as about the same for deaf inmates.