The judges opinion states that they did not demonstrate standing by filing lawful evidence that they were assigned the mortgage. No evidence is no evidence and is not grounds for appeal.
Furthermore, the banks can do one of two things. Find the right entity who has standing in this case - if one actually exists - or pursue an appeal. The latter course may fail because they lack grounds on which to appeal and in the mean time 27 mortgagees get to live "rent free." for a long time while this one wends it way through the courts.
My curiosity is focused on why this was in the Federal Court in the first place. Foreclosure on real property is a state law action (like garnishment, levy, repossession, etc.) Why did this attorney lodge this in Federal Court in the first place and have to face the diversity jurisdiction question at all?