Legal Question in Real Estate Law in California

No. You are WAY too late. If it's any consolation, the chances you would have had a successful case are pretty small anyway. First you would have to prove the sellers knowingly misrepresented the square footage and/or that your agent was negligent in not realizing that the square footage was off. Chances are your agents documentation was full of "deemed reliable but not guaranteed" for things like square footage, size of the lot, and anything else that could be measured if you had chosen to make sure it was right. Second, the fact that neither you nor your agent thought the square footage was wrong, suggests that it was not wrong by enough to be noticeable. Since the measure of damages in such a case is the difference in value between the house as represented to you, and as it in fact was, you would be faced with appraisal reports that the defendants would commission that would show that the house was worth what you paid for it regardless of whether the square footage was exactly as represented. A lot of factors go into the value of a house and square footage is only one component. This is not like a commercial building that will be rented by the square foot, in which case every square foot has a dollar value to a buyer. If the overall value of the property was what you paid for it at the time, you have no damages to sue for even if you had done so in time.

No.