Shir HaShirim is an allegory, not a euphemism (as Oomis said).
It is not meaningless when read literally, but the literal meaning is not the intended one. (In fact, it is assur to translate it literally, not that that stopped some Jews… ArtScroll describes their own Shir HaShirim
as “an allegorical translation based upon Rashi.”)
Okay, many more Jews speak Hebrew and English
than Yiddish, but how many non-Jews speak Yiddish?