We'll fix up the dialect issue in this chapter first tho. We wanted to convey that part of her character but I agree that we went too far, we'll tone it down and update this chapter first to make it consistent with the following chapters. Thanks everyone for the input. Please tell us again how you liked it after we update this chapter.
With your introductory note in mind, my suggestion regarding Elis's speech would be to
gently stress not only the casual gruffness of her tribal mode, but also the formality of the courtly speech she learned from Hinako. I say this because translations that try to replicate regional dialect via localization almost never work. But if you just slightly underline the structural differences between one style and the other, you should be able to get the idea across without seeming strange or silly.
You could, for instance, render Elis's "proper" speech in polite, precise and even somewhat stilted language without contractions or slang. The rougher style of her people could then be suggested by more-or-less normal contemporary speech: short sentences, simple words, standard contractions and a bit of slang. Where the former Elis would say "As you wish, onee-san," the latter might go with "No problem, sis." And "May I have your attention please?" could become "Listen up."
P.S. Great job so far! A thousand thanks for picking this up
