Henadic Theologian
Legend
If I had to do something with Kara-Tur, I'd play around with some of the basic stuff from the whole Hordelands idea.
It's been over a century, so maybe the Tuigan (pseudo Mongol) empire has survived in some form and it's at roughly the stage where it was under Kublai Khan, fragmenting but the Tuigan have basically established a dynasty in Shou Lung, (The Northern of the Two Chinas), and are planning to conquer the southern of the two Chinas, which I would rewrite to be more like the Southern Song which had been separate from Northern China, since the conquest of the North by an earlier group of horse-raiders.
There's quite a lot of advantages to this set-up. The Mongol empire led to a renaissance of silk road trade due to the peace they enforced, (Pax Mongolica) so this would see greater contact between Kara-Tur and the west; you'd have Red Wizards all over the place (as I said earlier in the thread if you look at the map Thay is closer to Shou Lung than it is to the Sword Coast. ) This also allows lot more cosmopolitanism. If people are travelling all over the place it's a lot easier to justify a range of characters. You also have lots of clear potential conflicts. The Tuigan in Shou Lung want to invade the southern China analogue, there may be a native uprising in China against the Tuigan inspired by the later rise of the Ming Dynasty. While in the Hordelands, the potential for fragments of the old empire to descend into war is rife, and one of the warlords might decide he wants to reunite the old empire and start a war with his rivals. (Since Semphar is vaguely Persian I'd probably have a Tuigan style horde there inspired by Tamerlane's court in Samarkand).
I'm not sure exactly what I'd do about the two japans, but one of them badly needs to be going through some kind of encounter with an outside force. Given the hundred years since Maztica, you could have trade ships coming from Maztica with silver which would lay a foundation for introducing something like the Wokou. Although if the parallels with colonialism are two uncomfortable, it could be something entirely different. Seeing as Forgotten Realms doesn't really have an Indian analogue you could have an island further to the west broadly inspired by Chola India or something like that (or make up a new culture based off one of the non-human species), just enough of a foreign presence to shake up the stereoptyical Japan and make it something more interesting.
There's also two buddhist Tibets for some reason. I'd rewrite one of them to be more based off the pre-buddhist Tibetan empire that fought against the Tang dynasty.
That's just a starting point, without bringing in more overt fantastic elements, (much more integration of non-human species is needed to make it fit realms better) but I think at least that much would be laying better foundations.
Actually the Forgotten Realms does have fantasy India, in Faerun, a few nations in the Shining South, like Durpar. The Koung Kingdom hints at a possible Kara Tur India (or rather a Sri Lanka which the writers never got to).