There isn't a HTD community, bottom-draco is hp general (that skews h/d because HD is a larger chunk of the fandom) but there was only been 3 (infrequent) fests. Most of the time, it seems mods (other than kitty) burn out doing the fest and disappear, so I think kitty is hesitant to bring in new people and do another fest - though capitu and I have offered to help)