Justoverclock I believe this should be ready for 1.0, it is now compatible with beta16 so I will keep an eye on 1.0 when it releases to check that nothing is broken.
admiralarjun This must be done separately on phpmyadmin or another script you might have, you just have to add a row on the table
flarum_achievements_user with the user_id, achievement_id, created_at (this is a datetime) and you can put the column new to 1 so the user will get a notification when they log in next time. This is only for very customized achievements or events that happen outside the forum.
admiralarjun I am not sure what are you trying to do, can you explain a little more your goal and maybe I can find a workaround for that purpose or I can modify the extension.