How can one request for a translator of a certain language to be present at Sydney Airport's border control, while travelling to Australia?
The Australian Department of Immigration and Border Protection provides a Translating and Interpreting Service:
The Translating and Interpreting Service (TIS National) is an interpreting service provided by us for people who do not speak English and for agencies and businesses that need to communicate with their non-English speaking clients.
Since this is a service provided by border control themselves, I imagine it would be available to non-English speaking travellers who arrive in Australia. You could call them and check to see whether there is anything extra somebody might need to do to ensure an interpreter for their language of choice is available.
If you know it in advance, one could prepare a paper with the common questions (max 10, better 3 or 4) and answers. This should be written on both languages, so that officer could ask you again a question to have confirmation from you. (knowing to say yes and no is also good, but head sign works).
The common questions (for travel) are: - travel alone, with family (indicate your family) - how much time do you stay? - where? (having a hotel address or hosting address helps, or itinerary) - do you have return ticket? and something to indicate that some people will wait for you at airport arrival (or answer how you can travel without knowing any word in English [a guide in hand helps])
I passed several time immigration offices without knowing local language. Usually there is no problem, and immigration officer will provide some translation (like above questions) in major languages, and they have also some translators, but... try to avoid it: scarce resource, so it will take time waiting.
Also usually there is some person who will help you. There should be (usually) many people who know "departing" and "arriving" languages. Just don't be the last in queue of your plane. (If you had a complex route, with several stops, this possibly is no more an option)