They need a "everyone else" bottle episode with the aforementioned plus Nillson, Linus, and Reno and none of the usual suspects.
Adira and Gray are third-tier characters. They've already spent a metric ass-ton of time on them compared to... where's Linus? Where the hell is RENO (love that character!) ?? Where are all the other third-tier characters that could also have had just as profound an impact on the story that haven't even had a
single line of dialogue yet this season?
Edit:
CV330 ninja'd me while I was writing this...
Yeah, I almost feel that "Short Treks" (which will likely not return now that they have a more full-slate of regular shows) would be needed just to flesh out these other characters correctly. I had completely forgotten about Reno, for example, who was introduced with such fanfare all the way back in S2...and then basically became an afterthought.
DSC would be better served if:
1. They focused on Burnham, Stamets, Culber, and Saru as the main cast, giving them the majority of focus, contribution, dialogue, and interplay.
2. Stopped trying to force Burnham into a romantic entanglements and focus any "relationship" stories on the existing characters of Stamets and Culber, who have a ton of material to build off of and actually could be meaningful and integral to our story lines.
3. Use Reno, Detmer, and Owo as secondary characters, in much the same way TOS used Chekov, Scotty and (to a lesser extent unfortunately) Uhura and Sulu.
4. Keep the others in the background as supporting players..., but not be focal to any particular story.
I guess now that Tilly is gone, you could bring her back occasionally like Wil Wheaton on TNG or (maybe more accurately) like Shran or some of DS9's players would pop in-and-out.
The issue is that DSC only has ~13 episodes to flesh characters out. You can't have 7-8 primary characters like TNG, DS9 etc because there just isn't enough time to give everyone something meaningful to contribute. So, focus on your "top 4" and then fill in as needed with the other tiers.