Mar 14 2016
@Billinghurst: I'm trying to take the point of view of WS and *not* that of WD. So when WD has a /clean/ modeling of the situation (separating items for persons from that for articles about that person) then there will be not only translations but a much bigger class of WS pages where the corresponding WD item will ever have exactly one sitelink but WS pages would like to link to ~corresponding~ (related, comparable) pages in other languages.
Mar 13 2016
What I was aiming at: There seems to be a general problem underlying this concrete issue: Wikidata items connected to some WS page typically (?) have exactly one sitelink (namely to the WS page in question) but still there are ~closely related~ items "in other languages" (*and* also the same language) which could be presented. So a rather general mechanism could be thought of involving traversing up and back down a ~suitable~ WD property and its inverse - but what property that might be should be under control of the Wikisource article - e.g. "edition or translation of" in the case of poems and "main subject" in the case of encyclopedic articles. I'm quite sure we'll find even more examples on closer investigation.
Just to give the issue another twist, here is something in between the original issue (different editions) and that mentioned by Purodha: