MA's law provides that the non-disclosure party is liable for the buyer/renter the "actual damage". Note that this is not "speculative damage", but actual damage, which is most likely is limited to the cost of lead paint remediation.
EPA provides that lead paint remediation including removal or cover-up. So essensially it is the cost of painting the hosue, maybe adding some lead paint overcharge to do it more thoroughly. You can ask for it if you have time. It's not going to make you rich.