tl;dr
As far I can see developers expect to properties being listed by the
community, but the listing is kept in a way that the community normally
looks as a draft waiting for complaints until some amount of time and later
being implemented... communication issues, eh?
BTW I've listed some properties on [1], all of them examples of ID
uniqueness being a non-issue.
The remaining user subpages may have also in the very exact scope, but I
will wait until the 'community process expectation' versus 'this is a thing
that will get done even no one says a word' gets clarified.
[1] -
https://www.wikidata.org/w/index.php?diff=311688067