You have excellent answer below.
The only other suggestion I can make is to have a face to face meeting between you, your Realtor, the sellers, and their Realtor, and figure out what can be done.
The best question to for your Realtor to ask the Listing agent is: "What can we do to move this transaction forward?".
You also might want to do an updated CMA and see if paying the extra property taxes, plus the purchase price, makes the transaction worth the price.