The ability to back-date course completions and events
The ability to add a past date to a course completion instead of today's date only. This is helpful when migrating courses to the LMS or migrating a system in general. I would also like to be able to add past events such as in-person training to a calendar within a course. Again, this lets me store historical data instead of pulling from various system.
Ivan Butorin commented
The API has method /v1/getusersprogressinunits/, which allows to see user's progress in a unit. However, there is no "set" method.
Such method would be very useful in the scenario of migration from another LMS: preserve current status of user's progress in a course, migrate their certifications etc.
Such method must have "date_completed" property, so that certifications that have expiration date would retain it.