We are using mandatory profiles in our VDI environment running W10 v1809. It may be a silly question, but can't really find a solid answer to this:
Do we need to update/recreate the mandatory profile after updating or upgrading our golden image?
Upgrading what in the parent image exactly? if you are referring to DEM, then the answer is no.
I think you need to create a new one when the version changes, look at the page, most current windows versions are using the same profile version.
Create mandatory user profiles (Windows 10) | Microsoft Docs