Hi hi hi hi! I have had a Terra's Grace question bouncing around in my brain for over an hour now, and I'm fiiiiiinally at a computer so I can ask it. Very excited! (And happy happy happy that I didn't end up forgetting the question, haha. It's a little bit wordy/twisty, I guess...) So, as long as answering this doesn't interfere with your plans for the story in any way...
I think it might've been a post from your blog a little while ago that got me thinking about mirror pronouns today. And then I was wondering, well, hypothetically -- if Society A has only one pronoun for people to use in its conventional grammar, and also has no contact with any other society with a different pronouns situation, then as far as Society A is concerned, for practical linguistic purposes it has no distinction between "having [person pronouns]" and "having [mirror pronouns]", right?
SO. If Society A later encounters & interacts extensively with a Society B that uses a variety of personal pronouns including mirror pronouns... To what extent would individuals in Society A stick with the 'traditional' single pronoun, versus deciding to use mirror pronouns instead?
i.e., in the context of Terra's Grace, where Chapter 10 states that Grace personally uses they/them for every Eridian except Rocky -- well, 1) will the professional Earth linguists even agree with Grace's interpretation there, and 2) if they do determine that the Eridian personal-pronoun-equivalent is really identical for each individual Eridian, would the most 'proper/accurate' translation of an Eridian personal pronoun into English be "[gender neutral personal pronoun, e.g. 'they']"? Or would it be "[mirror pronoun]"?
FASCINATING QUESTION and one which! I don’t have a good answer for lmao. I do think that the linguists would have preferred to go with a specific neopronoun for Eridian use (at least in English, I truly cannot speak to any kind of linguistics or pronoun usage in other languages but I know there's lots of languages that don't do gendered pronouns at all and more that don't do them quite like English does), maybe ze/hir since that one is a pretty old one with a lot of precedent. But Grace *already* established the precedent with the Eridians of using they/them pronouns for everyone but Rocky, so would they change that? I don’t know. I *don't* think it would become a situation where Eridians all get whatever English gendered pronouns assigned by humans.
Tldr I think they either stick with they/them or use a simple consistent neopronoun like ze/hir. EXCEPT for Rocky. He's specials.