Regarding language, my personal rule of thumb is this: Never translate names and don't use words that have suitable replacements. You wouldn't use the word Katana in place of the word Sword, but you would say it when talking about specifically Japanese Swords. 

Honorifics are a little more complicated, because you have to consider that the character might purposely be following a specific set of customs as well as the fact that Japan in general is well versed in both Japanese and English. In a earlier post I called our resident anime catastrophe "Miki-Hakase", which is basically like saying Professor/Doctor Miki. Normally, I'd say you simply call her Professor/Doctor, but you might want to distinguish between a character following English customs and a character following Japanese ones. In a text based medium, the only real way to do that is to keep both "Professor/Doctor Miki" and "Miki-Hakase" as options. Otherwise, most Honorifics do pretty much have translations that work just fine - it only strikes as not because honorifics are a bit outdated in English.