Long time lurker here - is there an open house or something like that you can attend? If so, I'd go to that and try to express interest there to the professors directly, because it seems likes it's hard getting programs to reply to emails when you're waitlisted. But honestly, if you have a fully funded offer somewhere else, I'd take that and not sit on a waitlist anymore! An offer of admission is always a better sign than a waitlist, so the program that offered you admission will probably be the better fit anyways. Especially since you don't know if you'll even get off the other waitlist, whereas the place that offered you admission definitely wants you. Congrats on being accepted somewhere!