The language Australia asks for
An English text is required for papers used in Australia. That single line is the whole of the language rule on this route, and it decides what you spend. A paper written in another tongue has to arrive with English beside it. A paper already in English arrives on its own and needs nothing added.
Nothing is done to the record itself. It is not stamped, marked or rewritten, and it stays in the form the office that made it issued it. The English pages are new paper, made from what your record says, and they are the only part that carries a signature from a translator.
Which papers are left in the pile
People in Edinburgh who send a file to Australia usually hold a mix. A degree from Warsaw, a birth entry from Manila and a Scottish marriage extract can sit in the same folder, and only two of those three cost money here. An official English translation in Edinburgh is bought paper by paper, so the sorting is real money, not tidiness.
Where the paper you need is a Scottish civil record, Edinburgh Registration Service holds those entries and issues certified extracts of them. Ordering a fresh extract is safer than posting the one in your drawer, because a certified copy can be reordered while the copy you keep at home cannot be replaced in transit.
What Australia accepts on the English pages
Australia takes a certified translation with a certificate of accuracy. The translator states that the English matches the paper it was made from, names the paper, and signs under their own credential as a certified translator. No court title and no oath sworn in front of a judge sit behind that signature on this route.
That is a narrower rule than some countries apply, and it makes the job simpler and cheaper than it looks from the outside. Certified translation into English in Edinburgh is done from the copy you supply, so the copy you hand over decides exactly what the English pages say.
Cost, speed and the order of work
The rate is about £25 a page. Two to three business days covers the standard run, and 24 hours covers the express one. Notarisation is on the menu if a reader in Australia has named it, though the certificate of accuracy is what does the work in most files sent this way.
One order of work saves the most grief. Get the record into your hands in the form you mean to file, sort by language, then buy the English pages for what is left. Doing it the other way round means paying for a translation of a paper you later replace.