they did not listen; they did not know how

The cliff notes:

-Not much of Yaeko's backstory is different from Yusuke's in canon. (She does look a lot like her mother, so she wondered if something was up with Sayuri, but it didn't click until she saw the full original version. Because of that resemblance, she avoids wearing red whenever possible.)
-Yes, she's still a tol beanpole.
-If anyone else is rule-63'd in her 'default' timeline, it's Makoto. Happy to play her off other rule-63 party members, though.
-She picked up a little more situational awareness re: how to work with a model, so the whole thing with Ann was less of a debacle.
-On the other hand, the final confrontation with Madarame's Shadow very nearly ended in his death.
-Forming a more genuine friendship with Hifumi, as opposed to Yusuke's 'we're in the same graduating class and that seems to be it,' since they're the Weird Girls even by Kosei standards. Could eventually mean she does some of the heavy lifting for Hifumi's Confidant link, and/or that Hifumi gets dragged into the party properly.
-Help, all of her friends are hot.
-PT outfit: Behold! (Art by ghosthotel.) The stripey sash with fox tail, boots, gloves, and mask are the same as Yusuke's outfit. She's still a katana girl.

Yaeko's most frequent canon point is the day after the Shujin crew goes to the TV station - and yes, they're all aware Akechi reacted to Morgana. There's just not much they can do with that yet except keep an eye out. Can be from further down the timeline by request.