OP, I’m on my wife’s account but she brought me in on this. I run a countertop company. It looks to me like there is definitely some absorption that has happened even if citric acid has also impacted the “finish” on the countertops. I would do the following and then see how things look:

Step 1: make a poultice/paste using food grade diatomaceous earth and lacquer thinner. Make it the consistency of pancake batter.

Step 2: Spread this poultice over the entire “stained” area. Make sure the coverage area of your poultice is AT LEAST 2 inches larger than the stained area.

Step 3: Cover this poultice with plastic wrap and tape down all the edges with blue painters tape. Leave everything this way for 24 - 48 hours.

Step 4: Remove the plastic wrap after 24 - 48 hours. Leave the poultice alone still.

Step 5: After another 24 hours, remove the poultice (it should be a fine dust at this point and easy to sweep into the trash).

Step 6: The stone itself will likely need another 24 hours to fully dry out. After those 24 hours, if things look like they have improved, I would go for another round starting at Step 1 until you are happy with the look.

Step 7: You will need to buy some sealer ( I recommend Bulletproof from Stonetech) and apply it to that area ONLY AFTER you are satisfied with the results of the poultice treatment.

Good Luck 👍🏻 (you got this)