I’ve always sort of wondered if/ headcannoned that the Starlights got the name order wrong and originally meant to pose as siblings. But then their record label manager guy (I know nothing about the music industry, sorry) was like “oh my god a boy band with all the same given names this is genius teenage girls will go gaga for this” and they realized they messed up. But it’s too late to change it because their manager has already branded them the Three Lights and has convinced them it’s a great way to reach a huge audience.
(I especially like the idea of it being Taiki’s mistake (since he’s the scholar they’d probably leave it to him to investigate culture and language) and Yaten never letting it go.
“Yaten you have to come to this rehearsal you’re not going to know the music well enough at our next concert”
“Ah yes I’d hate to make a mistake, wouldn’t I, Kou?”
“…”
“I’m not moving my hair appointment move the rehearsal time”)

So why does no one talk about Rei/Yaten?

I mean it’d be a train wreck but it would be a hilarious train wreck. They’d intrigue each other with their surface personalities long enough to get to dinner on the first date, but then each would expect the other to faun over them, and they slowly get more frustrated and less polished as the night goes on. Yaten slips in more and more passive aggressive jibes and Rei turns towards just plain aggressive but she really wants to rub it in Minako’s face that she can date a pop star so she doesn’t leave. And as much as Yaten is annoyed by the date they actually like Rei more than most people they’ve met because they have a mad respect for elegant fronts and they enjoy seeing Rei’s fall apart. And eventually theirs falls apart too much they insist it hasn’t and they and Rei are both just angry messes by the end of the night.

And then they agree to do it again soon.