Phew there's a lot of info there! takes a while to digest it all. But with general stats there's not going to be anything in the form of proof. I'm not sure if something like this is really provable without some kind of Chainalysis-like company doing thorough research. I fear we're mostly going to find out if it happened after the fact, unless somebody happens to get lucky and stumble on the missing clue.
I would prefer to be wrong though, and have these high prices be the success of Steem instead!
I know traders have separate communication tools that the public does not have access to... so I would doubt coordinated efforts would be that hard to organise... especially if there are potentially millions of dollars to be made... or lost.