Alas, our nascent AI overlord has missed the fact that ping-pong isn’t a cuisine (or to be a little fairer, that eating together was just one of the many relationship-building things going on in that visit, and not the most significant one) and its illustration of kimchi diplomacy was between two nations where kimchi is a commonplace dish (and would really better be described as “food aid” than “cultural diplomacy”). There was also a whole lot more going on with Gorbachev’s diplomatic efforts than sushi could come anywhere close to explaining. I don’t question that it’s good for tourism promotion, but that’s not the kind of “powerful tool” you’ll need in the wake of an imperial collapse.
The Rim alone is bigger than either Switzerland or the Vatican – more like Norway-sized. Rim-plus-Southriding would be a good sized country, not much smaller than Turkey in our world. Because the territory traverses the language gap, with by far the bigger population in the southern half, I don’t think you’d necessarily get away with naming it a “-lund”. I’d give the reader the chance to name it, with some suggestions, so you could go with Coruscant if you liked. 
Thanks to her, I’ve read a fair amount of anthropology in the past year, which shaped how I wrote the folk of the Xaos-lands in various ways. I’d already written the plant-stuff into the world before she properly started down this career path. But more plant medicine may find its way in based on the resources she now owns.
There’s never been a canonical printed version. It’s a bit like JEDP theory or the Q hypothesis, where there’s surely something to it – there were texts originally written in an old Shayarin dialect, that were edited in the process of getting to the final canonical Codex – but starting from the Codex as we have it, it’s impossible to get a non-coerced consensus about which bits were in which source.
Yes, with heavy reliance on the right allies… who will themselves have ideas on right doctrine. If your ideas are different from theirs, better specialize in CHA.
I’m going to continue to hold off on explaining this for a while. A lot of my reading over the past year (since I got access to academic libraries and research papers through my wife’s study) has been boosting my grasp of real-world military history and technology, the better to think through how Theurgy might have disrupted and shaped military strategy. Grateful for all of your patience and eventual feedback when I’m ready to put some provisional ideas out there.