If anything, I would just dial back on the Japanese humour. (The little 'argue like a married couple' skits with Penelo and his insta-enthusiasm as soon as airships are mentioned, specifically.) Doesn't work on my old Scandinavian funnybones...

I too think Square did a good job on Vaan and Penelo, making them plausible characters. So, Vaan isn't a cookie-cutter bona fide hero, big deal. Characters don't have to be paragons or help you through a life crisis to be well crafted, right?