Thank you for your reply.
Yes, something about the encoding is getting messed up when saving the translations in BO.
I already found that stackoverflow post and tried making utf-8 the default encoding in both php.ini and .htaccess but it still wouldn't fix it. But I will try checking it again thought.
Another thing I noticed is that prestashop will get show an error when trying to save japanese characters in the shipping estimate field. Maybe somehow related?
Would still appreciate any guesses.