@jonobie It seems the timing on Netflix's subs for this show did not receive much editing and proofviewing. The translation for the on-screen Hangul would be up for like a tenth of a second, but then someone would say something and that would immediately replace the previous subs.
My wild guess regarding the obvious explanations is that maybe a term was translated into an English self-explanatory term, but to a Korean reader, the original text might be using an archaic term.