Q:Our current design is such that once a user has completed a course, this information needs to be captured in our CRM system. Is there some sort of trigger we can hook into to know when a user has completed the course?
A:You could create Item receiver for GradeBook that we will trigger on any update of the item. It is possible to hook for the property gradeBookItem.Have Certificate.
As example like this
This suggestion has assumption that course should be configured to create certificate on completion.