Ah, ok, now I understand. The problem might be that we aren't using machine translated texts, but human translated. So when matching translations, often sentences don't have a 1-to-1 matching. Translators often change sentence structure to better suite the new language (there are even instances of translators adding new characters in the book).
You can look up more about that research from here: https://en.m.wikipedia.org/wiki/Extensive_reading