I'm not familiar with state law in Maine, but I don't think the abstractor has any liability unless he negligent in some manner.  I don't particularly think you would be liable for the clerk's negligence, so long as your client has been informed of the issue and they understand that you can only report what the clerk provides. 

The clerk's liability is also difficult to determine.  They may have some kind of limited immunity by statute. 

This does not seem to be a very sound pracitce, but I guess you can only do what the clerk will permit and the rest is beyond your control.