Has the Church ever, in any authoritative ay, even expressed an opinion about this? Whatever the case, it seems to me that the exact dates are hardly that important, whatever they are.
To my knowledge, the Church has never made a solemn
declaration on the precise date of the birth of Jesus.
But I would suggest that the immemorial use of the calendar and the constant use of the dating system is pretty darn authoritative.
Also, I have read that the census that the gospels seem to be talking about relating to Our Lord's birth would have taken place in 4 BC. Doe it really matter to anyone but historians?
Yes. This is a common attack on the Church. And it is
an attack to demonstrate that the Church is wrong about a pretty fundamental issue--the birth of God on earth. After all, if the Catholic Church is truly the Church founded by Jesus Christ Himself, surely the Catholic Church would know when her Founder was born. Other religious denominations know when their respective founders were born.
Get and read the book I reference above for an explanation as to why the objections that place the census, and therefore the Birth of Christ, somewhere between 7 to 4 B.C. are erroneous (and often deliberately so).