From my own experience on Hunterpedia, this feature is extremely ANNOYING, and more importantly, there shouldn't be any incentives to edit HunterX. The intention of creating an enjoyable, informative and reliable source of reference for Hunter x Hunter fans should be the only reason, not flashy badges.
This feature basically rewards anyone who edits a wiki just for the sake of editing, rendering the improvement of the overall quality a secondary goal. I have seen people spamming stupid categories on pages, making spam edits that don't contribute to articles and adding useless images to pages just to increase their edit counts. So, the achievements extention will never be enabled on HunterX.