Even within the fantasy post-racism, post-sexism, post-isms-in-general (except maybe nationalism and some classism I guess) Arx world I still find myself having to think critically about questions related to this thread.
Ex.: Katarina, for the folks who don't know, was born in the Dune Kingdom, a strange and mysterious land across an ocean from the setting of Arx. When I applied for her off of the roster, I outright said that I saw the challenge of playing the character as doing so in a way that isn't lazy isn't-she-exotic cod-early-20th-century-Orientalism. There's nothing WRONG with her profile as written on the roster, but it would be very easy to take what's there and just kind of play her as the descendant of any number of capital-E Exotic characters from fiction that don't necessarily speak to any particular truth, whether Lovecraft's Arab mystics, Disney's Jasmine, Dejah Thoris from Barsoom Which Is Totally Not Meant to Represent the Middle East or Darkest Africa Honest You Guys Really, Storm from the X-Men, whatever.
I still end up trying to find ways to set her apart as being Not From Around Here because I think it makes for a good character beat in a game where bloodlines play a significant part in determining who has the power, but I do my best to do so in ways that reflect that kind of post-isms vision of Arx -- she has a strong accent and her cadence and word choices are a little weird, as opposed to something stupid like showing up to a dinner party naked and smiling knowingly while trilling, "ah, but you Compact people, you still cling to these barbaric textiles?"
Ember, too, has her backstory where she's the first woman to directly inherit a barony in her fealty, instead of having to rule by technicality or regency. I can't imagine playing her as anything but intensely proud of that fact and ready to bring it up constantly until people are sick of hearing about it, and that pride determines how I travel other aspects of her character (e.g. not taking the always-ready-for-a-war "Bloody Baroness" and making her a force for conservatism in her fealty; if she was conservative, she wouldn't be baroness).
So, even though Arx has the built-in "guys, people just aren't racist or sexist here, so leave that shit outside," it still presents ways to question that kind of stuff -- just without the playing-with-fire aspects that people might perceive about real-world identities or cultures.
I mean, if I'm just talking out of my ass, please tell me.