...Fourth, it tells us that the large Ransaran population of Arcana enjoys a very high standard of living and describes that standard in language clearly intended to evoke the late 20th and early 21st century consumer driven societies of the developed world on Earth.
I believe that the combination of free movement of people and the "almost universally high standard of living amongst Ransarans" indicates that the Ransaran standard of living cannot be the result of exploiting the rest of Arcanan society. If Andarans or Multhari and Shakira caste Mythalans lived at a greatly lower standard of living then Ransarans I would expect large scale immigration from those societies to Ransar as well and we have no evidence for that. Differences in living standards on the scale of what is found today in the EU, or maybe even a little larger are believable, but they can't be much greater then that. That means the vast majority of Arcanans probably live with a quantity and quality of consumer goods comparable to what is available in the Developed World today.
Such a supply of consumer goods requires a very large "relative level of discretionary economic surplus" and thus shows that Arcana can devote a portion of its economy to war comparable to the portion that an industrial society can. If what I have said above is true then the "Hydraulic" versus "Industrial" comparison cannot apply.
The key issue is the Arcania Prime (and highly developed Arcanian colony world) "Magical power grid."
Arcanian developed worlds that have magical power grids can supply things like recharges to sliderways without magical individuals to provide them.
Thus the Ransaran standard of living and "advanced technology" may be a reflection of consumer magic goods developed for the non-magic talented with pure physical user interface having magic power grid recharge of spellware.
This is not true on most Arcanian frontier worlds with sliderways, let alone frontier worlds solely supported by Dragons and arcane-enhanced hippotrain.
Andaran military authorities would not develop or deploy such Ransaran magic technology for combat use on worlds outside the magic grids.
NB: I suspect that Ransaran combat forces on Arcania Prime are the highest firepower simply because they have the most physical interface only magical combat weapons attached to the largest Arcanian magic power grid...which cannot deploy far beyond Arcania Prime or highly developed power grid Arcanian sister colonies.