I'm generally with you, although I'd say the pre-Christian Celts had pretty distinctly different attitudes towards women than either the Classical world or the Christian world. Not peace-loving and matriarchal, but definitely different ideals.

I wish I could find Celtic historical fiction based on the archaeological and historical record without neopaganism mixed in. :-/

Anyway: when it comes to historical and modern-day fiction, I research until I absolutely hit a wall and HAVE to extrapolate. If the research doesn't work for the story I have in mind, I tend to pick different research. For fantasy I'm more flexible, although I think research-based fantasy tends to feel more solid and realistic.

I get the impression most people don't care nearly as much.