The problems with North Korean translations
The readers of NK News are probably familiar with the problem: sometimes you open an English book on North Korea, look at the sources section, and find that none are in Korean. In fact, it is not uncommon to see a thesis, article, or monograph based solely on English sources. Needless to say, the quality of such works is normally not high.
Theoretically, if every text written and every word spoken in Korean could be flawlessly translated, then, indeed, possessing command of Korean would not be necessary. But, unfortunately, this is unlikely to be the case until humanity invents a universal translator.