Something I realize I don’t know the answer to, help me Tolkien fandom.

Who is the (in-universe) author of the Lay of Leithian?

We know Dírhavel the mortal of the people of Hador writes the Narn i Chin Húrin, and Pengolodh as our author of a lot of the lore, especially Gondolin. Songs about Eärendil are very common, enough that Bilbo makes his own version. Maglor’s Noldolantë gets name-dropped. Elemmírë’s Aldudenië is known by all elves. We don’t know the authors to the various hymns to Varda/Elbereth, though between their appearance in LotR and Fingon singing a hymn to Manwë, I can assume there is a wide body of such devotional songs and some of them can be dated back to the Great Journey and before, what with the Eldar and universal star-adoration. Folk tunes, natch. So probably a mix of Silvan/Sindar and Vanyar/Noldor authorship. (Tunes from the Lindar as the first singers among the elves, though in Valinor I’d say Vanyar, as they’re the ones noted for composing songs and closer/more holy for the Valar, but the songs spread outside Valmar by the Noldor)

But if we go by explicitly stated most popular stories or those agreed as known and beloved

by practically all Eldar – it’s Beren and Lúthien and then the tale of Túrin, then hymns to stars (lumping Eärendil in this).

I’m assuming the author was Sindar. I think it would have been noted if was it another mortal composition in an elven style. It wasn’t Daeron. It sure as hell wasn’t Maglor. Then again, it would be really weird if the Lay was a translation of another of Elemmírë’s universally popular songs.

IDK, this feels like something Tolkien would have provided the Wastonian answer to.