I'm not sure if this is a suggestion or a bug report, but I noticed that if you hire a graduating idol as a staff member, they do not appear in the "graduated" list for idols. I figure they should still appear there, perhaps with a note that they were hired into the company in their bio. (It would also be cool if their mini-portrait could use their idol appearance instead of the generic staffer type, but I'm not sure if that's something that can be modified easily.)
Also, it would be interesting if idols who were dating a graduating idol (who then becomes a staffer) could continue dating. It felt funny to see "X lost mental stamina for a mysterious reason" when X's (ex-)girlfriend was her new stylist.
As a side note, I feel like this is out of scope for the intended tone and gameplay of the game, but I sort of feel like the game eventually starts to limit players who choose to maintain a low number of idols, and I feel like it would be interesting to have a mode that focuses more on a smaller group size. (Smaller max building size, less emphasis on multiple projects happening at once, etc.) The new Relaxed mode is a great help for a casual player like me to play in that manner without a game over, but a lot of features are based on much bigger groups after the first year or so. That said, I feel like my ideas would be better for a mod or a different game, so I'm not holding out hope on a small-time company mode.