Nothing you said here is wrong, but it also doesn't explain how likely or not employees with those common shares will have made money. Having been on both sides of these transactions, I think it's likely that they made very little on their vested shares, but they likely will have been given new hire packages with Atlassian that will be worth something (RSUs vs options).
Why do I think they didn't make much from vested shares? Simple preference math. While I don't know Loom's cap table, or how each round was structured, I think we can all agree that they gave shares to investors that at least had 1X preference. Given that the sale happened at a substantial discount to their last round valuation, it's likely that preferences ate up most if not all of the proceeds of the deal. There may have been a sweetener of some sort offered to the leadership team, and that may have been distributed to all existing employees, but that would have been independent of the cap table (they're not going to give a package to departed employees that exercised options).
Why do I think they didn't make much from vested shares? Simple preference math. While I don't know Loom's cap table, or how each round was structured, I think we can all agree that they gave shares to investors that at least had 1X preference. Given that the sale happened at a substantial discount to their last round valuation, it's likely that preferences ate up most if not all of the proceeds of the deal. There may have been a sweetener of some sort offered to the leadership team, and that may have been distributed to all existing employees, but that would have been independent of the cap table (they're not going to give a package to departed employees that exercised options).