No, you're STILL misreading me...
The Marches Imperial table should include Ardenese, since a small but probably highly spacer-oriented portion of the marches' Imperial pop are Ardenese.
But you should NEVER find a randomly generated Ardenese name much past, oh, say, Corridor.
No, you're not getting it. I don't use these tables to decide where an Imperial expatriate is from, I use them to figure out what ethnicity his name is. There is no such thing as a recognizably Ardenite name. If I get a result of Anglic, Swordic, Solomani, Vilani, Minor non-human, or Non-human, the NPC may be from Arden. If it's someone encountered on Regina, there's a very small chance that he is from Arden (More likely from the small community of Ardenite expatriates living in Regina Startown). If it's someone encountered in Corridor, the likelihood is a lot smaller.
Chances are I'm not going to care where he is from. But I do find it useful to know what his name is.
The various discrete human cultures that we know of include the Dlani of Illellish, the Ardenese, the Sword Worlders (who almost qualify as a MHR, since they got there by STL ships), the Psaydians (who don't go starfaring as a general rule) & Jonkerer (MHR - non-starfaring), the Syleans (who are, essentially, the default, and may be a hybrid of 2 or more ethnic groups), the League of Antares (who are a cultural enclave under the Archduke of Antares' direct rule), any of the known Pocket Empires of the Long Night...
Are the people living on Dlan a minor human race? I don't recall ever hearing that. Do you mean Suerrat? Anyway, the Dlani may have a unique and recognizable pattern to their names that scream 'Dlani!', but until and unless someone documents said pattern, I can't very well take any notice of it. Even if someone did, they'd probably be below the resolution of the tables I'm making -- a few billion names in 15 trillion don't really register if you're using percentages or even tenths of percentages (permillages?

).
As far as I know there is no such thing as a recognizably Ardenite name. Even if there were, what I said about Dlani names goes for Ardenite names too.
Sword Worlders have mostly Solomani names. Mostly Scandinavian and Germanic with a leavening of every other culture on Earth and even a few Vilani names.
The Pysadians may or may not have their own language (the evidence is too scanty to say for sure), but the same argument as before applies.
AFAICR the article about the Jonkereen (who are not a minor human race but a variant human race) does not mention their name an language at all, but again, there are too few of them to have an impact on a generic table.
The Syleans probably do have recognizably Sylean names (though a lot of them adopted Solomani names IIRC). They're not the default, BTW. The map on p. 102 of
Referee's Manual show Sylea as one of the cultural regions that "historically developed independent cultures and which have retained their cultural identity under the Imperium". Anyway, I certainly would expect to have 'Sylean' on my table, though I'd be a lot happier about it if I knew what sort of names that implied.
The League of Antares would have Vilani and Solomani and Vargr names, among others. But will there be any recognizably Antarean names? Not to my knowledge. Same goes for all the known pocket empires of the Long Night.
Hans