file:// page is completely not localized. What is needed:
• Translatable headers (Name, Size, Date Modified),
• Localized/translatable units with proper pluralization — especially important in the case of “bytes”,
• Localized decimal point in units (decimal_point under LC_NUMERIC?),
• Localized date format (%c?).
I did a quick search for 'Date Modified' and couldn't find it anywhere, so no clue where this page even comes from. But it's there in MiniBrowser exactly the same as in Epiphany, so it must be a WebKit-level thing.