I really wouldn't know, and neither would you or anyone else.
I've worked as a field-translator for a big military project between a security company from my country to a foreign army (yeah, I've led an interesting life...), and I can tell you that differences between languages are much bigger than mere syntax and vocabulary.
Not only that you can't replace word for word or even sentence for sentence to deliver an idea, but you also have to understand the
spirit of both languages and the nuances of their different spoken forms. And I really hope you don't have to translate slang!
If you want to know exactly what I mean, just ask uncle Google Translate
Also, the fact that the game is written, doesn't necessarily mean that all the text is laid down in all it's different parts and final form. And so you have to wait until you actually develop the game itself, before sending it to professional translation.
"Story" and "Script" are usually not interchangeable when you're dealing in cinema, games or even books - though in these cases, of course, the technical terms will differ.
But let me stress this: I have
no idea if this is the situation with this game and this dev.
He is the only one who actually knows what takes him time, and what doesn't.
I'm just giving my two cents here, because you raised some legitimate questions, which I think others have here, too, and I tried to answer you to the best of my abilities.