Can we track which emails have been sent and received by the learners?

There is a status column next to any email interactions to say whether they have been triggered or not:

This gives you an indication of whether Cohort Manager has instructed WordPress to send emails to the learners. However, it’s worth adding that this doesn’t necessarily confirm whether your system has successfully sent the emails, or whether the learners have received them. Tracking whether emails have been received would depend on how you have configured WordPress to send emails. If your WordPress platform sends its emails out via a 3rd party service like MailGun or SendGrid then these services tend to have detailed logs on email delivery.