[XIAODI PAN]

Under the current ATO guideline if the evidence is insufficient e.g the platform is unaudited and no other evidence can be provided it is both Part A & Part B.

Auditing SMSFs with crypto assets | Australian Taxation Office

Few of the platforms you can ask client to authorise you to request the balance report directly from the platform however this does not change the internal control issues of those platforms. if they are held in offline cold wallet ledger then there will be a public key or wallet address to verify then in the crypto chain.