Standard Latin characters are half width. Ｆｕｌｌ ｗｉｄｔｈ latin characters do exist, but that’s not the difference we’re seeing here, if anything that would make the Latin font in the English release “quarter width” except that’s not a real thing that exists. It’s just an ultra condensed font, and the fix is replacing the font files with more standard fonts, not some kind of special font to treat half width as full width.
Realistically it’s only katakana that you can make this mixup on. My desktop IME will let me type カタカナ or (reluctantly) ｶﾀｶﾅ, though it turns out iOS doesn’t have a way to type the half width kana, and IMEs have differing opinions on if they prefer full width digits, so you might see full width numbers like ５０００。
Realistically it’s only katakana that you can make this mixup on. My desktop IME will let me type カタカナ or (reluctantly) ｶﾀｶﾅ, though it turns out iOS doesn’t have a way to type the half width kana, and IMEs have differing opinions on if they prefer full width digits, so you might see full width numbers like ５０００。