If you need to highlight this in SFDC on the lead/contact record, then you will need to create some custom fields in SFDC to pass data to them from Marketo.
Could have a check box for Hard Bounced, and a date field for when this happended.
How to do this:
Create smart campaign in Marketo, in smart list section, is email address bounced is any, the flow will be to mark new check box equals true and use a change data value flow step, select your new custom data field and use a system date token {{system.dateTime}}.