Kosta on Feb 17 2013 said:
This presupposes that there were Nicene tables or detailed mathematical instructions which might be "revised". This has never been proven from documentation from the Conciliar generation itself. Documents from the Council of Sardica indicate that the Eastern bishops there (meeting at Philippopolis) intended their Paschal proposals to be a way of complying with the Nicene decision.
In 346 Athanasius in exile accepted a revision to Nicea at the council of Sardica.
In 333, Rome and Alexandria agreed on April 15th, which was the 14th day of the moon by the Alexandrian tables and the 15th by the Roman--too early in the lunar month by both Alexandrian rules (which normally set the festival to the 3rd Sunday in the lunar month, so the age of the moon would be in the range 15-21 inclusive) and by Roman rules (which preferred a lunar age of 16-22). This cannot have been an attempt to prevent Holy Saturday from falling on Jewish 14 Nisan. The only Passover date we have for 333 comes from the same Paschal table from Sardica already mentioned, which indicates a Jewish Passover (as always in the context, Nisan 14, not Nisan 15) on March 16th, 333. If some Jewish communities set their 14 Nisan to the following full moon, this would have been around April 14th or 15th. So moving Easter 333 forward to April 15th from the following Sunday would have increased, not decreased, the chances of it coinciding with Jewish 14 Nisan, assuming this would have been a problem for anyone at that time, which I doubt.
In 333 many scholars believe Pascha was moved back so Holy Saturday would not coincide with Passover, the anniversary founding of Rome, and the pagan holiday of Parilia.
The other proposal you cite, that the Romans objected to the later date in order to avoid having the festival fall when the merrymaking for the Parilia (April 21st) the Vinalia (April 23rd) and the Robigalia (April 25th) had already begun seems plausible and is accepted, as you say, by many scholars.