The EX Primals are generally regarded to have "no" accuracy requirements, or requirements so low it's hard to actually reach them. Probably 341 or 363 or something sub-400.

There are a few folks in the Monk thread who suggest that the accuracy varies depending on where you are attacking from based on a large amount of testing in their FC. E.g. rear = lower acc to cap than flank, which is lower than front. Sounds odd, but it would help explain why people generally find low acc ok, but we continue to see random misses into the 470 range on T5 -- particularly on "snakes" because players spend a large span of time attacking Asclepius from the front, usually. They are saying the rear acc for Coil is 435, flank is 458, and frontal is ~476 or something.