While I am not an attorney either, consider these questions:
Do you really want this home? If you do continue to wait out the process and work through the extensions. Dealing with the government on any issue can take long periods of time. If it comes to a point where there is another extension you typically have the option to let the home go. There are lots of homes available and another property may suit you better.
Do you really want to end up in a lawsuit? Typically lawsuits come into play when no other solution can be found or someone has done something wrong. As long as both parties agree to changes (extensions or any other changes) then I doubt nothing wrong has occurred. And often the only party that really wins in a lawsuit is the attorney who walks away with their fee for fighting the case. (BTW, I really appreciate my attorney friends.)