Hi Brendan,
Email Performance report does not report on the Emails that are sent by Sales Insight.
The email performance report gives you insight into the effectiveness of your emails sent by Marketo. It shows you how many were delivered, clicked, unsubscribed, and more. You can view this by campaign or by email.
However, You can create a smart list to find out the leads who were sent the sales emails by using " Was sent Sales Email" filter. You also have the option of selecting the constraint "Sent By" to see which sales exec sent the sales email.
Hope this helps,
Regards,
Priyanka