UserProfile.Manipulation.CSOM is needed on premises
Now we can update UP properties via CSOM in O365, but not on premises. I would appreciate if this can be included on-prem, my customers 80% of the time are still on-prem
We don’t really have a good status for this one, so using the most accurate one. CSOM based manipulation for user profile properties IS available in on-premises in SP2016 and in upcoming SP2019 versions. This is not, however, something which will be backported to the SP2013 platform, meaning that this capability will NOT be available from the SP2013 platform.
In SP2016 and in upcoming SP2019, you can use public method Microsoft.SharePoint.Client.UserProfiles.PeopleManager.SetSingleValueProfileProperty and public method Microsoft.SharePoint.Client.UserProfiles.PeopleManager.SetMultiValuedProfileProperty to manipulate user profile property values for a specific user profile.
Thank you very much for your input on this capability.