Sure they can allow an exception if they choose but if the neighbor complains of sound issues, they would be hard pressed not demanding the flooring be changed. The neighbor gets to stand on the rules; no hard flooring. if the board wants to spend a lot of Association money to attempt to prove the op’s install allows for no more sound transmission than the best install available when the rules were written, well, they deserve to be sued for improper actions costing the association members a ton of money.Why not? I can image an HOA board allowing an exception if its proven to them that the technology is even better than soft cover. They certainly have the right to do so.
So, since the complainant can stand there and say; the rules say no hard floors, the board is pretty much forced to enforce that rule regardless what the tech of yesterday allowed regarding sound transmission. They would be foolish to allow an exception if anybody complains about noise.
Btw; the sound issue isn’t just about neighbors below. It involves adjacent units as well (per the rules posted) and sound attenuation materials under the flooring will do little to prevent the sharp sound created when a high heel strikes a hardwood floor.