As there are many wikis with enabled ContenTranslation and so many published translations, graph of translated articles (especially in smaller wikis) in wiki's language is far too near to zero. From such graph is hard to read useful information about evolution on usage on the one specified wiki.
There should be option to "show only translations in the particular language" (and maybe to "show only translations in the particular wiki", especially after deploying ContentTranslation to non-Wikipedia projects).