One thing that troubles me about this(actually there are several things that trouble me)is that you mention "cardboard"...I have to believe that these speakers must have originally shipped in wooden crates with a protective mold to insulate the speakers.I have a pair of original design Focal Utopia's from the 90's and they were crated and shipped from France.Two big wooden Crates like a Vampire movie,big as coffins.When I bought these at a bankruptcy auction,bascially new for 6,000.00,they had no defects even though they had been stored for years after little use the condition of the enclosure was darn near pristine.
It is hard to believe that Focal would ship a delicate,expensive speaker in cardboard.Maybe I am missing some new cardboard that superman could not violate?
Another point,and to me this is the biggie on this deal....start negotiating with the seller for a monetary compensation for the speaker damage or they will be returned at his expense.We are talking 5 grand here bare bones compensation,at least,that is where I would start and if it goes nowhere get those speakers ready to go down his throat or up his whatever.If you are not a good negotiator,find someone who is,and get the ball rolling.
You need to get mad behind this and it sounds like you are treating this like a fender bender in a supermarket parking lot.Bottom line,your costly purchase has been greatly devalued right out of the box for ant resale.Go forward with nails out!