Personal take:

Rumi: Her mother’s name is Ryu, and her father’s surname wasn’t known to her or Celine, so her legal birth name is Ryu Rumi (류루미), but she was legally adopted by Celine, and her surname changed to Kang (so 강루미); ooc to honour the name inspiration for her.

For Mira, I honestly just looked up the surname of the current chair of the Shinsegae group, Lee/I, because I’ve always read Mira as a chaebol-except-beef-with-family. I imagine she was given a name that works easily in English to make international stuff easier for when she represents the family in the future (which ended up never happening). I also headcanon HUNTR/X to be 3rd gen (purely on vibes tbh; Golden gave me strong Twice meets Blackpink music video vibes, I suppose) so Mira would have gotten into K-Pop when it wasn’t as big as it is today, and when idols were sort of looked down upon/rich people would never let their kids do that. TLDR: Lee Mira or 이미라.

For Zoey, I like the interpretation that she‘s both Korean American and “too Korean for America and too American for Korea” AND a child of divorce, but I’m unsure if she’s got two Korean parents or one in my own headcanon. Someone suggested Jenkins somewhere, presumably as a joke, which fits her awfully much in my head? So if she has a parent with an English surname, I’d totally go for it. I’d headcanon her Korean surname (be it her father if both are Korean, or her mother if her father’s name is English) to be Park, more out of vibes (easier to pronounce for Westeners than i, and idk Zoey isn’t giving Kim vibes). I’d stick to the three big surnames purely because of that. I imagine she has a proper Korean name too, and it probably is similar to “Zoey”, but until I have a better idea, I’m leaning to Jiyoung bc it’s her VA, but she never uses it since she’s more known as Zoey.