If you go poking about this neighborhood you can see that they built a bunch of these boxes on the pillar foundations. Those pillars run all the way to the roof trusses. And that's fine. There's nothing wrong with a utilitarian box. But what they aren't is a higher quality custom with the taller interior ceilings and the bigger rooms and 2-3 car garages that go with a house that was originally built at twice the size. For example, the public zone of an 1100sf 3bd home is usually going to be a lot smaller than the public zone of a 4/3bd home of 2200sf.
We generally tell people that most room additions won't return their entire costs in the market. That if they want the 2200sf home it will usually be cheaper to go buy the existing home than to buy an 1100sf home and add additions. So if there's some argument about their costs exceeding an appraised value that would actually be a lot more common than not in other appraisals.
The other thing that's annoying about the lawsuit is the social equity argument, which has zero to do with what an appraiser does. It's not the appraiser's fault that the lenders practiced redlining or that appraisal texts published in the 1920s and 1950s reflected the values of those times. It's not the appraiser's fault that the cert refers to picking homes that are the most similar, including proximity, and that the value being sought is what the buyers and sellers would pay for the home with this location, not what the buyers and sellers are paying in other locations. The appraiser has no discretion about any of that, and loading those other problems into this allegation of misconduct is patently unfair to the individual being sued. \
Now there may be problems with what the appraiser actually did in this appraisal, but those actions should form the basis of the lawsuit, not what bankers did 70 years ago.