According to Southam, when the poem was first published as a separate
> poem, the title was "Perch'io Non Spero."
> Pound wrote an introduction to Cavalcani Poems in 1912, and Eliot may
> have first seen it there.
Pound did numerous translations of Cavalcanti poems.
Pound published a translation of Cavalcanti's "Ballata XI"----"Perche' non
spero di tornai gia' mai" in "Umbra" which was published in 1920. It is
also included in "The Translations of Ezra Pound" introduced by Hugh Kenner
and published in 1953 by Faber and Faber.
I do not own a copy of "Umbra" or "The Translation" and so cribbed this info
from Gallup's bibliography of Ezra Pound.