CASA's masterpiece ACVA is merely a day VMC exercise, involving flying at various fixed heights towards a PAPI during which the candidate has to identify the transitions in indications.
My (educated) guess is that the zealots' obsession with PAPI arises from the Tallahassee 727 NTSB report. They cling to conclusion 13 of 16 conclusions of the report, which conclusion is that: “The first officer suffered from a severe color vision deficiency that made it difficult for him to correctly identify the color of the precision approach path indicator signal during the below-glidepath, nighttime, visual approach to runway 9 at Tallahassee Regional Airport.”
Your refence to multiple clues remined me that the Tallahassee 727 had some sources of useful information: among other equipment, serviceable altimeters and RADALT. The latter is a particularly good indicator of height and should have been indicating 'not much' immediately prior to the impact with the ground short of the runway.
The simplest explanation for the incident, supported by the objective evidence, is that all of the crew were fooled by false 'too high'/'fly down' indications from the PAPI due to contamination from the prevailing atmospheric conditions. Up until the incident, the airport had never maintained or operated the PAPI in accordance with the manufacturer's instructions. The disagreement between NACTA and NTSB as to the condition of the PAPI at the time of the incident remains a mystery, as a result of which I'm trying to contact the author of the NACTA submission to the investigation. The submission contains some remarkable information including this: "According to Air Traffic Control Specialist Mike Peymann when he entered the TLH ATCT there was such an unusual accumulation of dew on the tower cab windows that he had to use the tower window wash system before he could see outside.”
Fact is that thousands of commercial pilots with CVD have racked up thousands of hours in command of transport category aircraft, day/night, IMC VMC and whatever, world-wide. Some countries remain in the dark ages on the issue of CVD. The current crop of CASA AvMed zealots is trying to drag Australia back there.
(AvMed's demands in relation to matters urological are typical AvMed overreach in response to catastrophised risks, despite the weight of qualified specialist opinion to the contrary. I've said it many times: Any idiot with access to the internet can do what they do. Find the most terrible potential consequence of a condition. Extrapolate that into an aviation catastrophe. Find the 'Rolls Royce' means of testing and managing the condition and, most importantly, ignore the weight of qualified specialist opinion and instead prefer the outcomes of an internal echo chamber 'complex case management meeting' because 'the safety of air navigation' is something that only they understand.)