In fact I try to help out with the SynoCommunity package, though in no “official” capacity. Will try to get a PR for including version v1.4.0 ready as time permits.
Regarding the permission management, so far I failed to grok their user and group creation code. It’s rather complicated because of the need to automatically transition from an older permission system in DSM 5.x to the current DSM 6.x.