Let me recap: you say
- this question has nothing to do with xowiki.
- editing the dotlrn form does not show at all with rte
- editing the form with xinha has trouble with Korean messages.
I assume, you are editing always with the client language settings of Korean. Correct?
Maybe the following can help you: xinha has its own javascript based message catalogs (currently for 33 languages, see packages/acs-templating/www/resources/xinha-nightly/lang/, there are additional catalogs for the plugins). I would recommend to add a Korean catalog named ko.js.