If you are working with an agent, please be sure to follow their advice over mine, as they are your local professional. Sometimes parties to a deal can start to make it so legalistic that they scare each other away. If you trust your inspector(s) and their report(s), then rely on that information to decide if there are any problems that would cause you to walk away. It sounds like there has not been, as you may be interested in taking the seller's counter offer to cover 1/2 of the repairs. In my state we don't use "release of liability", but we put it in terms of having satisfied the inspection contingency. They may want release of the "liability" of any repairs now & after closing. For the question of "is it common" you need a local professional. I can help you locate a local agent if you don't already have one. Does the seller have an agent if you don't? If so, ask that agent what they mean by the "release of liability".