Afaik only China and whoever did the transaction has access to the data. Which is interesting because like you say, such an arrangement only really benefits China (in terms of information) and is a minor drawback for other parties, yet in practice, nations still can't stop hugely lining up for CIPS.Is CIPS trade volume data publically available like SWIFT? At a glance on google I can't seem to find it.
A theory I've been hearing is with CIPS usage increasing it provides PBoC an information asymmetry advantage since they have access to both SWIFT and CIPS data, while US government only have SWIFT. Thus CPC has an increasingly more complete picture of global trade compared to US government. Does this theory hold water?