The 3rd objective is the core of the issue.
 
Let the creative people make what they want to, when they want to, personally put it on Rosearium if they want to, or upload it to the cloud and move on. How many TBs of photo and video are there already waiting to be posted “later”? That is where I’ll start because members will be happy to see “old” images.

Where we go from there depends on which of the options stakeholders pick. 

Increase uploads of exciting, exclusive content for any type of paid membership with little overlap. Find unique points to separate Rosearium from other social media outlets.

Drive members’ visits with a consistent posting schedule while also including randomly-timed and limited-time content. It’s possible their participation can be manipulated with conservative application of hashtags as they seem quite consistent in using #__ despite not being about to actually search for anything - at all.

Use management strategies to foster the illusory personal connection to the artists via direct bids for comments, occasional replies in comments, mentioning a topic brought up on the community board, and intermittent posts showing off gifts given through official channels, or any member creation that impresses an artist.

For many, part of fandom is bragging or otherwise calling attention to oneself. Along with things previously listed, give fans an opportunity to participate in decision making, hold one-off contests/drawings for items perceived as higher value, reward fans who are “most” of some category, and have limited Black Rose exclusive items that can be easily displayed when attending an event.