I see you need to go to the Help Center and read a few articles there.
In short. Viki has Korean and Chinese language dramas (and VERY few others). They come without any subtitles.
After the segmenting (you don’t need to know what that is for now), the English subtitlers listen to the original Korean or Chinese and they translate into English. Then the English is edited to make it grammatically and syntactically correct. After this is done, the other languages can start.
No team except for the English team translates directly from the original language. All other languages translate from the English. (Of course it happens that some Other Language subtitlers also know Korean or Chinese, so they can also be helped by this).
That’s why you were told that the only languages you need to know well is English (comprehension) and your language (writing).