Is there a huge story bible for the game?
Without getting into too much of our internal workings, I can say that we do have an extensive list of resources to draw on!

What happens if a quest is added involving a NPC that maybe hasn't been in use in 5 or 6 years? Do you have to go back to the original quests involving the NPC to get a feel for how they speak?
Oh, most definitely. Every time we have a Trust NPC with an accompanying event, I go back and look over all the quests they were involved in. In terms of the amount of time it takes to translate something, an individual alter ego takes me about three to four times as long as something more recent like the Tarutaru Sauce quests or the Seekers of Adoulin missions. These NPCs are beloved by the playerbase, so we have to do them justice!

The one exception was Ingrid, because she was released nearly simultaneously with her breakout mission and thus was already ingrained into my consciousness.