If a buyer's closing disclosure is sent to closing, and includes the seller fees, but at closing the seller's closing disclosure is modified by the title company. Upon receipt of the final executed package we find the seller closing disclosure has different fees from our buyer closing disclosure.

do we have to get the buyer closing disclosure re-signed again?

No - it does not impact the amount the buyer had to pay - it would be an uncorrectable error.

If the differences do not affect the amount the borrower/consumer/buyer paid for any costs listed on the consumer's closing disclosure, no.

I will say that if the title company conducted the closing on the bank's behalf, it should have produced a new closing disclosure with the correct seller's costs on it, on the bank's behalf. But since it did not, and if there's no change to the borrower's "bottom line," you don't have to produce another closing disclosure.

That said, if you WANT to provide the boyer with the accurate amounts, you are free to send an updated closing disclosure, but there's no requirement that you get the borrower's signature on it.