As a heads up, the Reserve Bank of Australia has a section labelled “historical data”: spreadsheets that with older back history. (Since these are back history, they won’t change.)
For the interest rate data (tables F1, F2), this would allow a longer back history of those series.
The spreadsheets appear to be the same format, with the same series identifiers, so it would just be a one-time splice of data. (I only looked at F1 and F2.) There are also monthly back history spreadsheets, but with different series identifiers.
The historical data page: https://www.rba.gov.au/statistics/historical-data.html