Creating a structure for regular planned activities can go a long way toward helping a transient burst of enthusiasm turn into a sustained social experience. It's good to set up spaces, but may also be important to e.g. set up weekly social THINGS even if it's literally nothing more than an e.g. Saturday chat thread or a show-and-tell newsletter or etc.
I like how much tilde folks have been excited and excitable about projects and stuff, but those projects can easily end up being solitary or fizzling out in isolation and the enthusiasm with them. Having actively supported non-project stuff to do together could make a difference.