What's the actual relationship to the Wing Commander series (or maybe even other Origin games)? Crusader is using the same dating system as the WC games (and placing it before those, as far as I remember) and the WEC is being mentioned in the WC series as part of terran history. Did you just add some WC references as easter eggs to the Crusader games or did you actually think of them as part of the same universe?
There is no relationship between Crusader’s universe and that of any other game. The designers liked putting in the occasional cross-reference to other Origin titles – like the crashed Kilrathi spaceship from Wing Commander that can be found on a farm in Ultima VII – but those were basically just Easter eggs and no serious thought was ever given as to how the disparate game worlds might be one and the same.
It's also worth noting that many of the screenshots included are from Crusader: No Regret, which is not available through GOG--yet!