I'm not sure we can adjust anything about the text box or font size, but we can easily add more pages (by page I mean a text box). Actually with my experimental script above I inserted 8 new page between the first and second page of the game.I might be wrong, but I'm wondering if the textboxes are adjusted to japanese characters and might need adjustement to fit in more english characters for the translations.
Kudos to you for making this work, I am excited and glad to see that an english translation of this game is definitely possible soon after its release. Thank you.