According to this article
Translation is typically considered a derivative work. While this varies from country to country, translation is considered derivative because it exists in relation to an original work, in this case a work of literature such as a novel or poem.
Even though it is derivative, translations are eligible for copyright as an original work. Since a translation, especially literary translation, involves considerable creative effort, labour and skill on the part of the translator it can be registered as an original work.
Thus my question is:
Is it legal to translate light novel works from Korea and publishing it on a website located in the EU ?
If it's legal, would it still be legal to do so when a US/EU company has the legal rights to translating it ?