While the standard dialogue is in English, and the game provides English subtitles in the cutscenes, it doesn't provide translations for the battle audio, Da Vinci's store, or Mash's speech in the various side menus.
I haven't found a subtitle option in the Game Options menu...is there a way to enable them?
Also, the game audio only works if I've plugged in the original earbuds, which is really awkward both because their store-band pods start to hurt after an hour or two, and because it means I can't hook the charging cable up while I play.
It's an iPhone 7, if the particular hardware matters.