It appears that the issue was dropped by the buyers agent, and the transaction has closed.
The issue would come up if you checked the box saying you have a EBMUD Sewer Lateral Certificate
then, unfortunately you are in trouble.
There are local requirements that both buyers and sellers agree to.
This is a EB disclosure.
Generally such a Certificate is a disclosure item, and clearly the Buyers and their agent dropped the ball.
Its a negotiated item
Guidelines for Buying or Selling a Property:
Obtain a Compliance Certificate before transferring title by fixing the PSL, if necessary, and then having an EBMUD inspector witness the PSL verification test (an air or water pressure test of the PSL). The buyer and seller will negotiate who will obtain the Compliance Certificate. Alternatively, you may request a Time Extension Certificate which provides an additional six months for obtaining a Compliance Certificate.
Clearly, your agents company attorney should be able to help you.