It seems that each consulate has differing rules regarding type of translations and which documents actually require translation vs which do not.
Prior to 2007, New York City did not require any translations of routine documents. By 2008, they required "accurate" - but not necessarily professional/certified - translations of the applicant's birth/marriage certificates, but none for previous generations.
New York always required certified translations for divorce decrees, presumably because of the more complex languange found in these as opposed to simple box titles ("Date of Birth", "Father's Full Name", etc) found on birth/marriage certificates.
Since the cost of translations can quickly add up, I would suggest you contact your consulate and ask exactly which documents they want translated and which, if any, require professional attention.
My hobby is finding things. Having found most of my own, I am happy to help others find theirs. PM me!
The difficult thing is actually contacting the Consulate. The Sydney Consulate has now literally closed the doors to walk-in appointments and my scheduled appointment isn't till December. I guess I should just persist with getting them on the phone (which has been proving difficult lately).
If anyone has any experience with the Sydney Consulate and knows the drill please let me know.