please help me deide: townhome which has foundation problem

The townhome which has foundation problem, inspector report that a couple (horizonal) mortar joint fractures are present in the foundation wall. This type of fracture typically occurs when backfill material is placed behind the wall too soon after the concrete masonry unites walls are erected or when heavy machinery is used too close to the foundation walls.

For this problem seller want to give $5,000 credit back. the seller agent told me need $5300 to fix it.

So If I take this offer, how much I can negociate? and when I resale this house, I already fixed this problem do I need to disclosure this information?

Welcome any comments.

Thank you!