This is the ABC Network report issued today. It refers to an Interim Inquiry Report, but it is cluttered with comment making it difficult to distinguish Report from other material.
Sydney Seaplane crash pilot's actions were 'totally inexplicable', says boss - ABC News (Australian Broadcasting Corporation)
The comment about a sharp turn seems to relate to a turn made immediately before the crash, not an inexplicable prior left turn off the main waterway into Jerusalem Bay. Along with others on TF I have never seen a seaplane enter Jerusalem Bay, I suspect that is key to resolving the Inquiry. At this stage the Inquiry is reported as seeking more crash witness information, and discovering what the plane did between landing at Cottage Pt. and picking up the doomed pax.