I found wrong Josa on Babel ko-kp.
In Korean language, Josa "은", "이" and "을" follow "조선말".
But now "Module:Babel" is expressed as Josa "는", "가" and "를".
For example, please see this.
Babel-<level>-n/ko system messages do not seem to call the parser function of Extension:Josa.
There are Babel-<level>-n/ko-kp messages in https://translatewiki.net that are not included in i18n directory in Babel repository.
@Nikerabbit has removed languages with only few messages translated, including ko-kp, in January 2017 (See the commit). I think it is time to reconsider about it and the statistics may help.