While I don't want to be overly optimistic or get anyone's hopes up too much - I don't think we know for sure that this will not help in terms of backlog. IRCC has clearly been making changes to processing, including sending files from some visa offices to other, less busy ones.This helps the initial processing stage but does not help with any backlog at any VO.
Do I know for sure that they might use some of this new capacity at Sydney to deal with backlog? No, I don't. But if Sydney starts taking on some additional roles or more work on files, that would be fewer files / less work at some VOs.
And of course there is some backlog of files that have not yet received AOR, this should help for that.