Dunno anything about that, but I set my speakers to super loud and blasted both of Xia's tracks a thousand of times to be sure and heard nothingI had the thing happen where the civ music played after diplomacy ended, so I got to listen to the Xia peace music loop for roughly 40 minutes. I heard someone talking at the end of each loop.
So I started wondering... do you have any plans for a Danube Valley Civilization mod or it doesn't fall yet into your considerations of Cradle of Civilization?
I completed a game with Harappa a couple weeks ago, and everything about it worked correctly for me. So it's likely that you're experiencing a mod conflict. Couldn't say for sure though.
Xia, Harappa, and Sumer should all be working fine. If you can post lua and database log files I can maybe figure out what's wrong, otherwise there isn't much I can do. It sounds like the lua isn't firing for whatever reason. (For Xia, dynasties change specifically when building a courthouse in an original capital, not just for capturing the city. Otherwise, it would be an issue with the capital plots not being saved correctly. Again, if you can post logs, I might be able to find out).