I confess I'm at a loss for the Italian, but Pound himself translates the
line

    "E 'l caso ghibellin ben seppe il fiorentino."  as  "And the Florentines
understood the Ghibelline case."

In the Italian version it is still part of the speech of Ezzelino as
indicated by quotation marks, but in the English translation the quotation
marks are missing.
    Perhaps the next line is quite appropriate.
    "E come onde che vengon da piu d'un trasmittente" which Pound separated
byan empty line in the Italian version, but not in the English, "Confusion
of voices as from several transmitters, broken" etc. This sounds like the
twittering of the voices in Hades which always follows the Homeric paradigm.
    We may wish Pound had found someone else to translate his own Canto. And
incidently, does anyone know of an English translation of Canto LXXIII?

CDM