Can't complete quest on attached photo
I tried to complete the quest with 100 bags
I'm just returning a message that the bag is full and I've got to clean it up and try again
Looks like that is because of the invalid item that quest still has. It will be removed with the next server restart and should resolve your problem.
I see on your screenshot that part of the text you have is in Russian. That is because you use an undefined translation. If you want your Korean translation to be correct and to have English text in case it has no Korean translation, then change your locale from "ko_ko" to "ko".
Changing from "ko_ko" to "ko" does not translate some quests and items.
The auction house cannot search for items in Korean. Items must be searched in English.
No that would require having someonen who speaks korean to translate it all.
With all the translations in the game that would need to be done it adds up in file size. Ar is already a large game and would like to avoid needlessly increasing it