I downloaded the RetroArch 1.5.0 and noticed the Korean localization added. but when I change to Korean language, no Korean fonts so menu isn’t appeared correctly.
Then I replace the Korean font (in screenshot: Malgun Gothic - default Windows Korean font since Vista) the menu outputs correctly now.
You can merge Noto fonts (https://www.google.com/get/noto/) or Nanum fonts (http://hangeul.naver.com/) in RetroArch. Both Korean fonts are OFL license.