Ranjah,
Probably the reason you were not considered a "language speaker" is because although you may be profficiant in Hindi it's currently not a language required by Australian Airlines. If they do start flying to India then it may well become a recognised language. As the web site says they are looking for Japanese, Cantonese and Mandarin. They are the 3 foreign languages officially recognised at the moment. There are crew that speak all sorts of languages but although they may be useful the 3 I mentioned are the main ones required for the routes they fly at the moment.
Also, to pass as a language speaker you must have the required documents as the web site states. Good luck.