Well, all this book has to say is that there's been almost no hard flat methods employed against them, because parents are almost entirely willing to avoid that day without external pressure.  More than half of them have at least one parent who's one of their geminis.  It's a short section, not even a full page.

Okay, what's his little book of all the birthday personalities and what they're like say.

Unuary 31:

   Affinities: They can be really friendly and good at doing favors!

   Enmities:  Often greedy and untrustworthy.

   Oddities: They're the least common birthday!  Having one of these as a friend is a rare treat.

It's notably more taciturn than even most of the even entries.

Wikipedia?

There doesn't appear to be an equivalent, at least in terms of scale and standout popularity.

..."What's the deal with Unuary 31s?" he asks the nearest Felicity.

"They have a bad reputation that in my experiences is at least partially warranted?  I'm sure trustworthy ones exist, but I never personally met any and - I don't think our society is very well shaped for bringing out the best in them."

"My book of birthdays was also vague, but as far as I know I haven't met one, what are characteristic things they might do?"

"I suppose - acting very friendly and generous but then demanding steep payment in return, even though you never actually asked for any of what they did for you.  Cutting out on deals the moment it benefits them  . . . They don't really treat children well, I think, even when they have their own geminis as kids; there might be something cyclical there - in general they make it very difficult to sincerely cooperate with them in lots of ways, I'd say.  You personally might manage it with enough bribery.  But if it were me I would dole out small installments of goodies at regular intervals, with the threat of stopping in the event of any nefarious behavior."

"Got it, thanks." He makes a note of this.

"Anytime.  . . . Just wondering, have you given any thought to where all the resurrected stars are going to live, for the ones who can't just pick up their lives again and don't have positions as PAs waiting for them?

"Is there a major living space shortage? I suppose I could have somebody summon an angel or three and excavate some cylinder, although I don't know that living underground in large numbers is actually good for people, what with sunshine and ventilation issues."

"Less a physical space shortage and more of a societal space one, I would say.  And - I'd have to read a few papers to refresh my memory and check whether the scientific understanding has updated, but I think it's been calculated that gravity applies to celestial light in convenient amounts for future people living on the edge of the cylinder.  What about ventilation worries you, that people will be . . . blown off the edge?  - Or do you think we have vaccum lower, we don't, it's all air."

"In my universe, people exhale carbon dioxide, which plants reprocess into more oxygen, which people need to breathe. Plants require light, but if light's handled plants can grow down there, I suppose, I did notice earlier there's water throughout the cylinder."

". . . I think we're talking past each other but I'm not sure what questions could resolve it.  Do . . . hm, no . . . are you worried that - I don't know."

"If you went into a completely sealed room and hung out there for a few hours what would happen?"

"I suppose I'd die of malaria - unless resurrected star clouds need all of their bodies to die at the same time in order for it to work, assuming it was only part of me - but I don't see what that has to do with this."

"Okay. In my universe, the word 'malaria' means bad air but it refers to a disease caused by microorganisms transmitted by bug bites; I'd call dying of being in a sealed room for air-related reasons 'suffocation', do you have that word?"

"I think here we only say suffocation when somebody is prevented from breathing entirely, like if they're choking.  If they can breathe but the air isn't life-sustaining that's malaria."

"Okay. And what makes air life-sustaining in the open, that a sealed room lacks?"

"It's as you said with the carbon dioxide, I believe.  Our molecular terminology is different but from an initial check I think it's referring to the same thing."

"Which is why I expect plants to be called for underground, for air filtration. You can do it mechanically with enough electrical generation, but plants are multipurpose."

" . . . I think the miasma is pr - oh, do you mean - I was just picturing shuttling off the edge and going at it from the side; you meant starting from the top, working your way down, and keeping everything fully contained?"

"You could also go from the side but it seems like it would make it harder for people to travel and be a little precarious... Anyway, ventilating to the side doesn't actually help much? In my model, which I'm assuming is wrong somewhere but I don't know where yet, where a room doesn't have to be completely sealed in order to not have enough carbon getting out and oxygen getting in to the air supply. So if the total number of plants does not scale up to match the number of breathers we run into trouble, even if it takes a while because there's so much air to begin with in the world here."

"It's entirely possible I've filled my heads with too many science fiction paintings of the cylinder seen from afar and giant holes filled with futuristic megacities carved out of it.  Although so have an awful lot of other people and you might get some mileage out of playing to that image - what did you think I meant when I said I thought gravity applied to celestial light in convenient amounts for this?"