Wow, I last left this timeline in the 1830s or so, and now I've spent a few hours looking at bits and pieces of the story, comments, and maps, in an attempt to get some idea of what's happened over the next 70 years. There's still huge stretches I haven't read, which I will try to do when I have the time!
A few thoughts-
I really like the idea of a world where the defining ideological conflict of the 20th century will be based not on opposing ideas about economics but rather opposing ideas on culture. In OTL, of course, there have been opposing views on whether cultural homogeneity or heterogeneity is more desirable, but those have mainly played out within countries, with people arguing either that a strong common language, culture, and sometimes religion are necessary to hold a country together, or that diverse languages, cultures, religious beliefs, and other types of identity are a source of strength. Even the most extreme proponents of uniform culture, who are certain that one culture is objectively superior to all others, never seem to follow the societists and openly advocate that the entire human race should follow one culture. On the other side, even the most extreme proponents of diversity don't go as far as the diversitarians here, who seem to advocate a kind of government-enforced diversity. Maybe I've gotten the wrong idea from my skimming, but that's my first reaction.
I get the impression that all written descriptions of the ATL are supposed to come from written material from within the ATL. That's a good way of telling the story, since it highlights the fact that we are looking at fallible sources that each have their own bias.
One text stated that nuclear [carytic?] weapons had been used more than 40 times in several different wars - holy s**t! On the other hand there seems to be a general agreement to not use them against cities and actual arsenals and delivery systems seem much more limited than in OTL (ICBMs sound like they are forbidden and instead nations are required to use super-complex suborbital bombers, if I understood it right.)
I feel bad for Japan in this TL. I feel even worse for India. China and Korea (sorry, Corea) are doing a lot better, though. Not to mention the Ottomans and Persia and the Maori (can't remember what the last are called in the ATL). Overall, the Europeans and Euro-Americans don't take over quite as much of the world as in OTL.
Haven't read much of the text on the actual Pandoric War (they use more poetic names for some of their wars than in OTL), but from what I know of how the technology is different in this world, I wonder if the weapons will be similar to WWI but the communications tech much less advanced (pretty sure they don't have telephones, let alone radio, until after the war.)