hey! the reason why some accounts are "left over" is because blocking needs to be done slowly over time to prevent your account from getting locked. you can view the accounts queued to be blocked from the context menu found by clicking the addon's icon in your browser's toolbar.

as for the repeated messages, I've experienced that bug as well and I'm not sure of the cause, but I'm looking into it.

regarding unblocking, the addon will not re-block a user you've unblocked when you click "undo" from the popups (or "never block" from the queue viewer). however, if you manually unblock them, the addon does not yet detect this and know to safelist them. the best I can suggest at the moment is to wait for them to be added to the queue and then click "never block". I'm sorry I don't have a better answer yet.