That is indeed an interesting point. The article states they use function words. Assuming that there is an injective relation between those function words in th

That is indeed an interesting point. The article states they use function words. Assuming that there is an injective relation between those function words in the original language and English, I could imagine that the translation would make it easier to compare (translated) foreign text to the normalized English database. As opposed to comparing the same function word in (say) Italian to that word in English.