I heard a few different opinions of who authored הא לחמא עניא. Does anyone have any REAL historic proof of the author?
Hasidim say its the Ari Zal, while Sfardim says its not
To summarize the comments, NO, no one has any "real" historical proof of the author. The Wikipedia page for Ha Lachma Anya gives a whole wide range of time frames that it might have been written:
According to Rabbi Yaakov Lorberbaum's Ma'aseh Nissim, Ha Lachma Anya was first recited after the destruction of the Second Temple in Jerusalem; according to Maimonides, Ha Lachma Anya was not recited before the Temple was destroyed. Shibbolei ha-Leket states that Ha Lachma Anya was instituted in Israel, while the Malbim and Ra'avyah trace the origins to Babylon. David Arnow notes that some sources state that Ha Lachma Anya originated during the Gaonic period (circa 750-1038 CE), while others trace it back as far as the first or second century CE.
The only conclusion that can be made is DoubleAA's that it was not written by the Arizal (or anyone post-Geonic) as the earliest versions of Ha Lachma Anya are found in works of the Geonim.