"The bathroom is at the end of the hallway."
Translation:Aia ka lua ma ka hopena o ka holoē.
Interesting comments about the word holoē. I used to think the same way until one day I was talking with a Niʻihau woman (many years ago) who had lived almost her entire life on Niʻihau, and when describing her house there, she used the word holoē. Her knowledge of English was pretty limited, and she obviously just accepted it as a good Hawaiian word. Guess that's the same with the word lumi which is used by everyone even though it comes from English. So now I have more respect for the word holoē. If it's good enough for a native speaker of Niʻihau Hawaiian, guess it's good enough for me. :-)
Perhaps, but change can go both ways. Hawaiian almost disappeared because of colonization by English speakers. To me, moving the reborn Hawaiian language back towards English would be a recolonization. What matters more than Hawaiian words being reborn is Hawaiian thinking being reborn. I would rather that Hawaiian grow in a direction that reflects it's origins rather than toward the language of those trying to colonize it. I'm grateful to have recently discovered an online class with a teacher who refuses to use English cognates (e.g. holoe, kiuke, hape nuia) and who looks first to other less colonized Polynesian languages as a source of new words. Just because someone comes from Ni'ihau doesn't mean they understand colonization. As a Hawaiian actively searching for the Hawaiian side of Hawaiian history, I choose not to use cognates for the same reason that I never buy anything from the Dole company.
That only matters if you're thinking in English and translating word for word. To me it's more important to learn and use the native thinking patterns of the language you are learning, rather than finding out how to map their words onto your thoughts. Many indigenous people give directions according to the cardinal directions, e.g. Aia ka lua ma ka 'ao'ao hema o ka hale. Aia ka lua ma kai o ka lumi kuke. I understand that this question is set up to emphasize English thinking, but you can report problem questions like this to the developers via the link at the bottom left of the screen that tells you the answer to the question, and in the discussion forums like this.
Hawaiian uses o as an indicator of possession, so ka hopena o ka holoē is literally "the end of the hallway" - the hallway's end.
I don't know of an overlap in usage between o and i. What you may be seeing is that o is used after locatives such as lalo, luna, waho, etc, in phrases such as ma luna o ka hale "on top of the house."
Does that help any?