Perhaps the phrase "People from the East" refers to the Priscillianists, who were often called Manicheans, thus being described as coming from the East.
Particularly interesting is the ending of this canon where the synodal fathers forbid the false presbyters and deacons to serve at the altar, if "it is not the matter of the well-being of the Church" (sic!). One may wonder how big were the pastoral needs in 4th-century Gaul, that in order to remedy the apparent shortage of clergy, bishops were willing to accept heretics performing church service.