The governing documents of the condo association require that if the condo association's reserve funds are to be used for repairs of the building, notice to all owners must be given, and votes of owners of 67% of the condos and 51% of the mortgage holders must approve.
Since this is a requirement of the governing documents that does not appear to be duplicated in state law, the penalties for noncompliance by the board should be laid out in those same governing documents. But I'll go out on a limb here and guess that they aren't.
Do the condo owners have grounds for complaint here, and against whom: the building (which doesn't really help us), or condo board members personally? What are our damages: the amount of dues increase, perhaps?
Definitely not the amount of the dues increase.
To figure out possible damages, you'd have to think through what would have happened if the board had followed that requirement. Obviously if 67% and 51% had approved, there would be zero damages all around. But if fewer owners and mortgage holders had approved, then what? Would the board have had the power to raise dues or make a special assessment back then? If so, owners who have sold their units between then and now might have gotten a bit of a free ride at the expense of future owners, so some recent purchasers might be able to show damages. On the other hand, if the board did not have the power to create a funding source at the time and would have been forced to leave the facade unrepaired, how would that have affected everyone's financial well-being compared to what actually happened?
The Cliff-Notes version: damages will probably be very difficult to determine.
Who would pay those damages? Possibly the board members, but in practice that would mean the insurance company that carried their errors-and-omissions liability coverage, paid for by the condo association. If the board members were unpaid volunteers, as is usual, that is as it should be, morally. Unless the board members personally benefited from their decision (for example, one of them owned the facade-repair company).