At first I thought it was an automated thing until I got this suggested edit in the review queue.
Clearly this edit isn't any good and in fact it wasn't posted if you check the actual question.
But in any case, why did the Community user edit this particular question? I thought maybe it is was a anonymous user, but those aren't usually replaced by Community user.
No, this is just a review audit you have experienced.This is just to check if you're actually going through the queue and not just pressing some button. It's not in anyway suggesting you're a bad reviewer BTW. For more information, refer to this thread and this Question.
The reason it's the community user is there is just a random choice. Sometimes I think It's also a randomly generated username.
And for who mad the edit, it was a script that used a system called the Markov Chain which can generate random sentences that seem to make sense but don't.
Why you get the error: When two users get the same review audit, the second one get the message "This item is not reviewable". After the first reviewer review it (regardless of fail or pass) other users get the message like:
Review audit passed(or fail) XX mins ago: reviewed this XX mins ago: Reject/Approve/etc... (source)
This item is not reviewable. So I'm pretty sure I wasn't audited :P If I was, then the audit system is getting weirder and weirder.