Think I can explain that. Simple analogy: you say Florence, not Firenze, right? Many English place names and proper nouns have been given Chinese or Korean versions, heaven knows by whom, and we do tend to use them when speaking in our respective languages. I doubt anyone here who picked up Italian would start calling that city Firenze when speaking in English, no?
Its not quite that it's a Korean word for Vancouver, but a Korean pronunciation of Vancouver.
Let me explain. First, written Korean is very easy, having an alphabet that was actually designed for language:
https://en.wikipedia.org/wiki/Hanguland
Under this form, it is actually written in 'blocks' each of which is a Syllable of the word. So for English Speakers, we know Vancouver, has three syllables: VAN-COU-VER. It's korean counter part is:
밴쿠버, which is also three syllables: 밴 (Pronounced Ban) 쿠 (pronounced Ku) and 버 (pronounced Ba)
Just like Korea, is our poorly pronounced Western way of what was actually one of the Three kingdoms that made up Korean back in the 12th/13th Century or so when discovered by Arab explorers.
https://en.wikipedia.org/wiki/Korea#Three_KingdomsSo, in a nut-shell, One of these three Kingdoms was 고려 (고 - Ko/Go, 려-Ryo or Lyo depending) which was a shortening of an earlier 고구려 Goguryeo or Koguryŏ (고 Ko/Go, 구 Gu/Ku, 려 Ryo/Lyo)
Of course this what we westerners (and likely most asian countries as well) call Korea, but for Korean they call their country Hanguk (한국) which translates literally as Country of the Han (What they call themselves).
Ultimately my point being, if Someone never knew there was a city called Vancouver, and they overheard two fictional Koreans talking of said place, yes the Koreans are using the English word, but due to limitations of their native language for certain sounds they are mispronouncing it. So, this Vancouver is heard as Bankuba, which could be further bastardized as it travels through a few more languages.
Another point is, I have a hard time pronouncing the few Korean words I know. I know most English is spoken with the tip of the tongue against the teeth, and most sounds are formed at the front of the mouth. Korean, I've learned is spoken near the back of the mouth towards the throat, and often with the lips pulled into what could best be described as a grimace (lips pulled back on both sides).
Finally, I like to think of the Inner Sphere map/names as the best representation of the current viewer/maker. Some fictional person.
Example being, using our Real World, we have the following Countries (That I know personally are NOT what they are called to natives of those countries), and I will apologize now for getting it wrong, but that then goes further to prove my point:
Germany (Deutscheland to German people)
Japan (Nippon to Japanese)
Korea (Hanguk to Koreans)
and that's just me.
So,maybe this IS map with all it's misspellings etc, is the ComStar Version. Capellan IS maps might have slightly Different spellings based on their local dialects, Same with Draconis maps, Steiner Maps, etc.