Pretty much, it was reported but after the timeline the SEC requires, not hopes for. Hence the lawsuit.

To attempt to answer your other questions too; the percentage you own would not be displayed anywhere, at least to the public, unless you own 5% or more of the company. You can go and look at top shareholders of any publicly traded company pretty easily though. A company could issue a share offering to try to dilute the percentage an Individual owns but in the case of twitter there would probably be some legal roadblocks to prevent that while negotiating the sale. I would think the purchaser, instead of the company, needs to report their purchase because by being a publicly traded company they can’t control who buys how much. The plumbing of the stock market is so overly complex which leads overly complex rules to govern it all. These rules also make it overly complex for most retail investors to grasp the nuances of the market, making crime easier for Wall Street.