I guess part of the question is "What is 'it'?" Does 'it' mean "our best and most accurate calculation of the day of birth" or "the day we should schedule a group celebration?"
Sometimes I even wonder what the "most accurate calculation" really means. Does it mean the day of the year in which the planets today are most closely configured around the sun in the same positions as they were at the time of Epicurus' birth?
Exactly! It is almost impossible under any definition to pinpoint an exact date correlation between an ancient event and the modern Julian calendar. The best we can do with something like Epicurus's Birthday is to respect the spirit of the Will. Those two papers I posted get at the highly complicated exercise calculations like that would be.