Sometimes the best appraisals are the ones that do not get made.
On more than one occasion, I have talked potential clients out of getting an appraisal because they did not need one.
The condo board, IMO, just needed a letter from an appraiser or RE agent stating that it is speculation wrt the unit sold for less. Nobody forced the seller to ake the offer, and the condo was obligated to disclose its carpet rule to buyers.
Unless the buyer is interrogated and hooked up to a polygraph, it's impossible to know whether they paid less because of the wood floors, the garage conversion, the unit being dated, or other reasons.