On Sun, Aug 21, 2016 at 9:34 PM Lars Aronsson <lars@aronsson.se> wrote:
If you look at this chapter of a novel in the French language,
https://fr.wikisource.org/wiki/Le_Voyageur_enchanté/Chapitre_1

...it has a link to the corresponding chapter in Russian
and next to the word "Русский" is a little arrow ⇔ or <=>

If you click that arrow, you get the two texts placed side-by-side,
https://fr.wikisource.org/wiki/Le_Voyageur_enchanté/Chapitre_1?match=ru

But there is no further matching. Paragraphs are not next to
each other. If I understand correctly, this is the "Double Wiki"
extension,
https://www.mediawiki.org/wiki/Extension:DoubleWiki
https://wikisource.org/wiki/Wikisource:DoubleWiki_Extension

Is anybody using this feature in a serious way? Does it have
any more details that can make the matching better? If both
texts had numbered paragraphs and sentences (something like the
Bible), it would in theory be possible to match them by number.

In most cases one sentence in the original does not correspond to one sentence in a translation. In many cases, one paragraph in the original does not correspond to one paragraph in a translation. As long as the Double_Wiki tool is a general-purpose tool for comparing different language versions, it's going to be massively limited in what it can do in these fashions.