Thinking on it more: I don’t think the purpose is necessarily linked to “otherness”, but rather to invite you into a different culture. When you research a term like that, it brings you into that mindset and cultural context.

Consider a fictional example: the slang in Shadowrun. I know it might feel a bit goofy to see stuff like “chummer” or whatever, but at least when I’m playing the Harebrained Studios games, it really helps to draw me into that setting, because those terms have very localized meanings.