Reading your Coran analysis (which is great) I'm left wondering how Coran would react to purple!Keith. After all, he's probably known a lot of teenage Galra in his time, considering how close their races were. He could just consider Keith easier to take care of, he knows more about Galra than these odd humans he's been trying to parent :D
It’s hard to say for sure?
I mean, Coran went very quiet on the subject, which- again, that kind of moving to the background thing, but I feel like that’d be potentially nerve wracking for Keith if he’s picked up how Coran tends to sort his feelings- it might even be scarier for Keith to try and broach the topic with Coran because Allura, at least, is pretty honest if she’s not feeling good about something.
Now, I don’t think Coran would just calmly harbor a grudge on Keith the way he does Zarkon- that’s a lot of orders of magnitude different, and I think part of the thing is here… Coran has the advantage of age on most of the team. A certain amount of him can’t really not see Keith as a kid, and one in a vulnerable scared place at that.
I still think he’d put up a poker face and default to his sort of mild-mannered-but-blunt attitude on the subject just because… I feel like there’d be health concerns, with the team. Something is suddenly happening with Keith’s body and they’re not sure what triggered it or if this is just a symptom of something else, that’s worrying- and he can’t afford Keith getting shy and folding off away from the team at personal cost, because I’d assume that much like Allura, regardless of how Coran might feel about having had a secret galra on the team, I think he’d feel stronger about potentially endangering Keith because of it.