I do admire your writing but you also seem a bit biased when it comes to comments on Christianity.
The gospels are generally considered historical documents even by agnostic academics and are pretty historical. Luke is no different.
The census Luke is talking about is likely around 6BC. There is a common mistranslation here over Quirinius. It should not be translated as governor as but the word used is hegemon meaning procurator. In other words Quirinius was in charge only of the census and the date matches up fine with Herods life.
The census was likely a Jewish one (to keep the peace) and not a Roman one and therefore had different rules.
Luke uses the word ‘first’ so his readers understand that this was the first of several census’ that Quirinius was involved in.
This account holds up fine.