Achievements are processed every so often (I forget how long in between) which is why new players create achievement spam. If you aren't online, it won't give you the achievement until it processes them again while you're online.
The main page of minecraft.novylen.net is a bit outdated. The last post was from a week before I joined the server. If we aren't going to use it for news, I suggest either someone making a video advert of the server on the main page or just general info on what the server is, what mods we use, and h...