Earlier quoted context omitted.
Which is to say, the original authors didn't care and were just writing latinesque gibberish that sounded cool. One of the critically important things to remember about 40k lore is that the game was originally a joke . Their "real" game was Warhammer (the game to be later called "Warhammer Fantasy"). Originally it was just "Let's put space opera tropes onto a game board and have them fight D&D monsters". Then they sh…
It was more than just a joke. It was a satire on England and 1980's society. The "Imperium," which is led by the possibly-dead body of a entombed demi-god, sustains its control over the galaxy with a mix of intense faith, authoritarianism, and a massive space navy with marine shock troops. That's England! The Imperium is the British Empire. The dead-God Emperor is Jesus and the Imperial Cult is the COE. The Imperial…
Well... while I buy that to some extent, I think the point is oversold. While there are absolutely satirical aspects to the early game[1], they're mostly limited to puns. What (original) 40k is absolutely not is subtle highbrow comedy. It's a bunch of drunk nerds guffawing about whatever they thought was funny in the moment.
[1] Which again, didn't actually include a lot of the later lore. Like, the emperor in the 1e rules was entombed but strongly implied to be actively leading the empire. Likewise the original conception seems a lot closer to dystopian sci fi than "1980's society" to me.