They don't seem to have a web site yet. And if you google for their name and exclude the words "formally", "spearhead", "vowed" and "debut" from the search, practically all mention of them disappear, which means that apart from two specific press releases, nothing is known about them.
They did get a cursory mention on a ProZ.com powwow page on 28 September, though.
Grammatically, that is...
Well, adding a "the" in the original name would probably also work.
..., apart from the fact that an AATI already exists.
Yes, I think it is a good idea to try to get an abbreviation that is not yet used in the same industry, although it is not an entirely unique situation:
Associação Profissional de Intépretes de Conferência (Brazil)
Association of Conference Interpreters in Portugal
American Translators Association
Association of Translation Agencies
Asociación de Traductores Profesionales
Asociaţia Traducătorilor Profesionişti din Moldova
Hawaii Interpreters & Translators' Association
Houston Interpreters and Translators Association
Institut Supérieur d'Interprétation et de Traduction
Istituto Universitario per Interpreti e Traduttori di Trento
[Edited at 2012-10-05 11:38 GMT]