Well, seeing as the DS versions are just Ys I&II Eternal with touch screen mechanics and the option to attack manually (which I think is a first for any version of Ys1 and 2), wouldn't the script from Eternal work just fine?
There's already been a translation patch for both on PC, I'm sure if anybody with the skills to inject it came up, it wouldn't be too hard to get a translation on them both. At least for all the old things that carried over.
Might want to get Deuce's permission to use his script if you care about that, otherwise seems viable to me.