Ok, I am going to ask this question with an Analogy. A Locksmith is walking in the street and comes across a door. The door seems to be well secured to a normal user and is actually a door to safe deposit vault/ stock exchange etc. The locksmith notices something unusual the Locksmith has an account (but no safe deposit) himself in the bank. Concerned the locksmith waits and see unusual activity like people who don't look like bank employees loitering around the door. He also observes that the security is so bad that it might be deliberate ignorance. Also, the Locksmith is a convicted (Ex CatBurglar) so him observing and reporting this can give the wrong signal to authorities.
Another analogy to this is an ex/reformed "Some Amateur Troll" observed "Some Country X Trolls" on a "Big Network" but can't point fingers and also cannot approach both cause he legally cannot say "Country X Trolls" activities benefit "Big Network" and "Big Network" might be simply naive or maliciously ignoring such activities for their own benefit.
How does he inform stakeholders legally?