http://en.wikipedia.org/wiki/Cultural_Revolution
... Okay, admittedly, the actual, RL Cultural Revolution didn't work out so well. It seems like a total-cultural-conversion uplift would have a fair few of the same aims without ... y'know ... famine. Regardless, the Caldari uplift apparently worked.
(Or maybe the city population has just grown way-fast since, what with abruptly super-modernized medical tech or whatever-- at any rate, it seems most modern Achura live in the cities as full-fledged Caldari.)
This seems likely, to me, considering we're talking about a society that was completely pre-industrial - Only a tiny percentage likely lived in the cities. Actually, since they probably take up a comparatively very small amount of the planets actual geography, it wouldn't surprise me if culturally Achur Achur still sort of think of the urban areas as fairly isolated pockets of harmless foreign influence in a world that is still, largely, theirs - Despite the fact that they've grown to the point that they outnumber them.
Hrrrrrm.
Perhaps for some, for a while?
The center of Achur civilization pre-Caldari apparently was not the monasteries, so I'm pretty sure they noticed that all of a sudden the government was full of weird space ghost people running everything. Once everyone concerned worked out who was running things on behalf of the rural Achura, some of the more isolated ones might have kinda gone "meh" about the whole phenomenon ...
... but I'm not sure I see that outliving, say, half a century. The Achura are pretty curious, observant, and pragmatic, so I suspect somebody somewhere got a hold of, say, some urban census report and went "ZOMG." Even if not, take it from a DUST player: Caldari planetary structures are not subtle and they're not small.
There's a certain five-objective map that has a Caldari version and a Gallente version. The Gallente version is pretty low-key, and consequently tends to involve a lot of plinking from long range: the facility's in a low-lying area and you can snipe right over it. The Caldari version of the apparently self-same facility? Um. It's taller by five to twenty times, depending on which bit. You can forget sniping over it unless you can get up on top. Most of its lowest buildings are about as tall as the tallest buildings of the Gallente facility, and its tallest are towers with peaks roughly level with a dropship's flight ceiling.
That's a pretty consistent pattern for Caldari architecture throughout DUST.
If the Caldari set up a city on your doorstep, you'd notice. If your own dwelling was a wood or earthen hut, you'd notice a whole lot.
(Also, come to think of it, Achura who wash out of Caldari society on the Achur homeworld are probably some of the luckiest nonentities anywhere in the State. When told to get out, they likely have someplace to get out -to-. Such travelers are likely to carry all kinds of news.)