In that case, however, I think it would not be fitting as a subcategory of WaniKani anymore.
I don’t really know what would be the best course of action – create two “Milestone Celebration” categories? One in WaniKani and one in Campfire? That might be overkill or get confusing. Are there even that many people that want to create their own topic to celebrate achievements unrelated to WaniKani, like finishing a book? Or would they just post in another thread, like for example Celebrating is a must?
Looking at the length of the Master List of Study Logs, a “Study Log” subcategory in Japanese Language or Campfire might actually make sense? 