Is it possible that apparent errors in early maps are a device for high latitude deformation? The eastward 90degree bend may be intentional in both Piri Reis and Vallard maps , as the linear distance to the end extremity is correct for both , with the low latitudes sections being correct.

https://en.wikipedia.org/wiki/Piri_Reis_map
The longitude changes eastward at Buenos Aires 35S (and correctly 8deg west of the Amazon mouth) by measurement of proportions of Amazon to Recife Brazil. The distance B Aires to the cape of Queen Maud land , in Antarctica, is then correct. As 'Indonesian' Hindus settled Madagascar from the 8th century, then due south from Madagascar to the Maud cape may have some meaning for them. Yama god is linked with the south.

https://www.google.com/search?q=vall...Qsob__T0Qc_tDM
The Vallard map of 1547 held by National Library, Canberra Australia, also changes eastward at about 32S . My comments about "Botany Bay" and "Tropic" are from this version of Vallard which restores the changed longitude to a presumed original survey.

https://commons.wikimedia.org/wiki/F...ap_rotated.jpg

Vallard has South at the top so this is the more normal style. If the lower extremity is taken to be the Murray river mouth (in South Australia) because of its resemblance to Coorong lagoon on the Murray , then the section to Wilson's Promontory (in Victoria) can be given a proportionate value for 750 kms . The total length to Cape York ( top of Queensland) fits and then the inlets can be matched to geography. The section to "Botany Bay" measures 950km north from Wilson's Promontory which accords with the distance to Nelson Bay.

Nelson Bay is a safe port to enter by sailing ship with low inflows of fresh water , which can be supplied at Kore Kore Creek , which is above sea level at 8 metres, beyond 10km inside headlands, behind Corrie island . By contrast , Newcastle's estuary extends up to the tidal limit of the Hunter River at Oakhampton (65km from the ocean), the Paterson River at Gostwyck (75km from the ocean), and the Williams River at the Seaham Weir (46km from the ocean), with strong outflow. Nelson Bay is about halfway to Fraser Island, the mid-point of the coast, and the northern inlet above "Tropic" is about half-way between Fraser and Cape York. Fraser-Cape distance of 2000km is correct on the map. Fraser island has safe anchorage north and south and abundant fresh water. The map seems to locate fresh water and safe anchorage at equal distances.

Stradbroke island fits the map drawing at 550km, with 250km on to Fraser Island. The inlet below "Tropic" fits Sarina 680km (Vallard 750 km). It is shallow and not emphasised like the inlet above "Tropic" which may be south of Ayr. Rocky Ponds creek flows down from 82m to the beach , sea depth 21ft. Ayr is 900km direct from Fraser island (Vallard 950km) and the geography fits the shape of the drawing.

There are 2 islands which are correctly drawn :
Cape York -Honiara , in Solomon island 1900 km .
Brisbane -Norfolk island 1470km . Vanuatu is further out , Cairns - Vanuatu 2100kms. (Vallard 2400).

The map over-compensates longitude eastward ( maybe demonstrated by Vanuatu?) , perhaps from copying the Piri Reis method blindly and without knowing the polar distance. Having 2 maps with this oddity when the basic form is correct may mutually validate them for their purposes. The Murray river mouth may be the end-point because Chinese and others went by boat on the river to Echuca in 1856 to reach the gold-fields.