Event Logs Should show all actions performed regarding any specific order (and/or subscription) by staff/admin.
Log should also show date/time
Status Update Changes
Payment attempts and success/fail
Sent Emails/Communications
When notes are updated
Discounts/coupons/other adjustments added, changed, or removed.
Basically any time there is a change, action, or update to an order it should be reflected in the event log of that order, including when/if a customer does something on their end.