I think you did a good job at the translation overall. The only things I found odd were a few pronouns. Especially the 'they' at the start when Millet was talking about staying up. I think that should have been 'we'( same with vivi saying you instead of they) .
Now I can't read Japanese, but I do know that they omit pronouns in most cases, so I'm just speculating as Millet not sleeping either makes more sense to me story-wise.