This label of the Dark Ages was applied to the Middle Ages by the folks that lived just after the Middle Ages who thought of themselves as better — so sort of a form of chronological snobbery if you will — and which is easy to do and easy to make up these stories. But when you look at the evidence you find that during the medieval medieval period yes the church had a Christian Church had a very strong influence in society and in fact they were the number one supporters of astronomical research. I know of a prominent historian of science, John Powell Braun, who is definitely not a religious person, who’s documented the church has been the number one supporter of astronomical research over centuries of time, not just in the Middle Ages but into to the early modern period as well.
What is of interest to the Traveller is that, when visiting the backwater worlds, it is most likely religious institutions — from the Babylon-style astrologers and star chartists to Church-backed scientists and observers — who are most likely to have some interesting data that was overlooked by others. This is especially true when uncovering things that happened in the past, like dating nova’s and impacts.
And this is not only true in the past: The Church of Stellar Divinity is sure to have a vast treasure trove of stellar data, right across the Imperium, and it can be safely assumed that other religious organizations have their own set of records that can be data-mined and cross-referenced profitably… if you know what you are looking for.