I downloaded this mod, but the civ name and city names have some sort of glitch in them, where they have a long string of (what appears to be) broken code in front of them. Doesn't make it unplayable, but does get annoying.
Despite whatever revisionist nonsense you've heard, the Civil War was most certainly "about slavery." That's why the general population in the North was so ticked off at the abolitionists; they blamed them for the war. Today, we should honor them for the same reason.
The states' rights at issue in the South were two in number: 1) the right to remain slave-holding and 2) the right to leave the union in order to remain slave holding.
Bottom line: If you take slavery out of the equation, then the Civil War would've never happened.
The OP is right to keep the CSA mod focused on such an agenda, anything else--like your assertion that it takes fifth grade naivete to call a duck a duck--would be an insult to the generations of Americans who suffered under slavery in this country and belittle the work of people who pushed for human rights above capitalist expediency in the decades that led up to the war.
Saying that the Civil War was about Slavery, OR States Rights solely is like saying that WWII was started all because Hitler hates Jews, or that the Stamp Act was the only reason for the American Revolution.
It was a mixture of the two, along with several other things. The states right's fight, which had been being argued for just as long as slavery in the US (in otherwords, since the start) had been coming to a head due to the "northern" (here, I regret to admit that for the sake of simplicity, I will be referring to a somewhat stereotypical view of northern and southern states, with "northern" states being those that, typically, were industrialized, anti-slavery, republican, and in general, in the north, and southern states being typically agricultural, pro-slavery, democratic, and in the south) states, who had recently gained a slight majority in congress, attempting to force the south to switch to their way of life.
This included (but was not limited too) the abolishment of slavery. it also included extreme tariffs that benefited the north at the expense of the south, as well as other laws that I cannot remember right now, because the Civil war is not my histiorical specialty. However, there was never a fight for equal rights to blacks. (in fact, it is held by some that the north was, and in some places still is, more racist than the south, due simply to the fact that blacks were less common in the north until the great migration after the civil war).
The south believed in "nullification". That is, that since the USA was a cooperative union of multiple, independent states (which was true when it was founded), that the state should have more power than the union itself. Therefor, they felt that they should be able to keep their way of life.
Eventually, when the differences became to much for the south to bear, they decided to do exactly what the 13 colonies had done 87 years before, and succeed. however, the north, being rather hypocritical, decided that they couldn't allow that, and thus the civil war.
It should also be pointed out that Lincoln would have gladly enslaved every black in the nation to end the war, and indeed, he didn't free blacks in the union itself until AFTER the war. (the emancipation proclomation freed only those slaves in areas still held by the confederacy, despite the fact that since it was another country, Lincoln had no right to do so).
The idea of a Civil War about something other than slavery is not the product of the revisionists. rather, the revisionists are what gave us "all about slavery" viewpoint in the first place. It was one of the first truths lost to them, actually.