English is very definitely dead in 40k. Gothic is a stand-in, the Faux-Latin isn’t actually old Latin given new life, it’s just base for representative gibberish.
Sure, in the Imperium being concerned about it, it’s a nonsense. But this is a forum with real people making observations about how lore accurate it would be to have fantasy people with those ranks giving us orders, or if having x or y accent would be correct in the setting.
I guess I just don’t see where Misozi’s accent or presence is more nonesense than is usual for cinematic storytelling devices or the 40k universe.
Again, the Rejects aren’t representatives of a Chamber Militant of the Inquisition, they’re not Stormtroopers, Sororitas, Astartes, or even Guardsmen. This is Grendyl’s war, run with Grendyl’s private army under his auspices as his own affair, and the warband is run more akin to a private business or organized crime cartel than a Guard regiment, where many hats are worn by disparate people.
Hence the comparison to Wagner and Bakhmut, where retired/disgraced Generals were personally flying strike missions to support convict mercenaries storming a salt mine filled with WW2 weapons at the behest of a former hot dog stand owner, who’s forces operated and were drawn from all across the world. Misozi being both pilot and acting Comms officer shouldn’t be a huge issue in a situation like that, nor should her accent being different be out of place.
More to the point, 40k is wildly inconsistent within its own lore, both intentionally and unintentionally, and different authors/games/animations/comics/etc can portray directly contradictory events and views, and it all changes over time. You can have one author write something where they note Imperial Law says Thou Shalt Not Do X, and another author will write a story or game will come out where they do X all the time. Dan Abnett, primary writer for this game, is somewhat famous for this. The entirety of the Space Wolves canon is a gigantic mess of mutually exclusive and directly contradictory traits and views where they can’t decide if they’re actually bloodthirsty killers or if its all a calculated act, if they’re total partybros looking out for the little guys or fanatical grimdark executioners of the Emperor’s Will. Guard regiments can be everything from battalions to entire army corps or even as shorthand for all troops from a given world. The Death Korps were famously brutally anti-psyker with no mention of their use from the point of their inception up until Fatshark came out with a Psyker skin for them. Etc ad nauseum.
London can be as cosmopolitan as it wants with people having accents of all kinds. That doesn’t change at all the existence of a british accent that is common and quite stablished in 40k.
Most “fantasy” stuff in general defaults to a British accent as a base, but 40k also makes it clear that its language and descriptions are a filter for modern readers (initially 80’s and 90’s era UK tabletop gamers) to understand, and isn’t supposed to be literally how or what people are speaking in the the 41st Millenium, which would be complete gibberish to them.
I guess I just don’t see where Misozi’s accent should stick out as an issue, particularly given the aforementioned context of Grendyl’s warband, and the array of other accents and ethnicities present in the lore and this particular game that are very definitely not British.