Okay, here's the deal. I'm making this post with a number of hats on. There are various player, reader, and general RPG denizen hats, as well as a mod hat, so the tone of this post is probably going to flow back and forth between all of them.
I've received complaints from readers that the entire costume thing, both with Youmu and Ran, is creepy (and not a good kind of creepy). Between multiple facets of the story trying to blow it off (Ran's established lack of tolerance for such things, Yuyuko faking Yukari out when deciding on dress for Youmu), readers being disgusted and turned off by it, and the sudden dearth of activity from players I expect are equally uninterested in such pursuits, I think it needs to stop. Someone needs to make up some off-hand answer to Yuyuko most recent question about the subject, and then no one ever broaches it again under penalty of removal from the game and possibly RPG on the whole (unless it somehow becomes story-relevant, which's I trust Purvis to avoid doing). There is a difference between private, semi-harmless embarassment and public humiliation, and however much fanon wants Touhou fans to believe that Yuyuko and Yukari can violate Youmu and Ran as much as they please under the guide of "teasing" and never receive any comeuppance or hatred for it, Purvis actively tries to make characters as real as possible. A realistic Youmu and Ran would never ever put up with what fanon does to them, and a realistic Yuyuko and Yukari, if they had half a decent bone in their bodies, would never initiate that stuff. So it ends here, and we all get back to play that is relevant to forwarding the plot of the story and doesn't make spectators and other players throw up in their mouths.
The then-obvious question, I suppose, is what to do from here. Personally, I think people are hung up on the details of this mahjong tournament, which is most likely the other contributing factor to the dearth of activity. I'm guessing everyone is at least somewhat reluctant to step on toes, which ends up devolving into a death spiral of no posting -> no knowledge of other players' opinions -> fear of posting and saying something other people don't want to do -> no posting -> etc. You all have a good foundation for this tournament idea - thoughts on several potentially interested players, a location, and a prize. I'd say these are enough that you can trust Purvis to iron out the lesser details in postgame. So let's move on to other things.
I'll come out and say that I don't think anyone needs to feel obligated to stick around with Yuyuko, especially since no one appeared to have an actual reason that going to Hakugyokurou was an immediate need. There have been other avenues of exploration given, ones that are more likely to provide enough action that the playerbase won't be confused and bored enough to start a mahjong tournament on a whim. Perhaps a little more chit-chat with Yuyuko is in order, including a decision on that dinner invitation, followed by leaving and pursuing likely-more-meaningful interests. Pretty much anything other than this continued lack of posting. Start anew, with no more major mess to clean up, and let's get somewhere with this game.