Do you have an agent that you are working with? That is the person that should be proactive and get your answer. You mention that there is a seller's agent, but no mention of you having a buyer's agent. It can take months to get a short sale approval from a bank, but that is about to change. New regulations give lenders 10 days to approve a short sale just passed through legislation. There are not a lot of lenders that would approve a loan when the home on leased land, as you likely discovered.
Behind the scenes, there is no guarantee that your offer is the only offer that is being considered. Often, out of need or out of aggravation, a buyer will withdraw an offer and seek another property. Short sales are about the biggest headache that buyers and agents have to deal with - hopefully, the new regulations will speed up the process. Good luck.