I think the problem is partly your technology path, partly your civic choices, and partly your overexpansion, with a little bit of Wonder-addiction thrown in.
Civics and Related
Too few workers. Six Workers for ten cities is too few - even with Serfdom, or looking at it another way 'especially' with Serfdom. If you're running this civic (which I think is not the best choice here) you would want an army of Workers to make quick improvements to your terrain before switching to Slavery (needed here) or the Caste System.
I would leap into Slavery and start whipping Courthouses. You've recognised this in that two of your ten cities are now working on Courthouses. Whipping them will decrease your costs through smaller populations and the decreased costs through the building itself. Cities with unhappy citizens (there are some) will lose these unhappy citizens first.
You are also running the expensive civic 'Vassalage' yet you're not in war and have only one military build at the moment. If you plan to get Knights and attack Mansa with them, that's fine, but otherwise if it's peaceful-development then I'd forget Vassalage.
You are in Organised Religion (good) but there are several cities without Hinduism. The spread of this religion will help their building production through the civic, improve happiness, open up new building opportunities (Temples and Monateries), and add a little

through shrine income. Your capital is building a Galley, but I'd start churning out Hindu Missionaries so your cities can benefit from Organised Religion.
Technology
You've made science and city management very low priorities in your technology path. I can see that you want to embrace the Mongolian warmonger philosophy, but it's killing you in other ways.
- 250AD - Writing
- 740AD - Currency
- 1070AD - Alphabet!
- 1090AD - Code of Laws
This is 'really' late for these technologies, and the result is that Hatty and Mansa have run away technologically.
Wonders
The Wonders that you've chased are not bad by and large, but I would think about what the opportunity cost was. Stonehenge for a Creative civ isn't totally useless, but the benefit of this Wonder is helping non-Creative civs to get their first border pop. It was there, it's cheap, and you have Stone - I can see the temptation, but I'd skip it. The Colossus is only so useful when you've got very few coastal cities who aren't working many coastal tiles, and generally haven't got commerce-oriented infrastructure (Libraries aside). The Oracle I can see - but did you use it for Monarchy? The Hanging Gardens is a pretty handy Wonder and would have been cheap given that you've got Stone. Health shouldn't be a big issue at Prince level, but it's still an understandable choice.
From Here
Now that you're getting your empire together better, I would re-think your civics, and if you're not planning to muster up a lot of Knights then swap out of Vassalage (> Barbarism ... if nothing else it's cheaper) and Serfdom (> Slavery). Once in Slavery, use the whip.
More Workers, more Courthouses, more Hinduism spread (and given that you've also got the Confucian shrine, there's some low-priority opportunity to get that religion spread too).
With enough Courthouses you should also build the Forbidden Palace that will trim your costs further. You can gear up for further warfare when you have access to better units - perhaps Grenadiers and Cannons, although you could do more than OK with Knights and Catapults (Machinery > Guilds)? I think that your empire at the moment is a 'sleeping giant', and could dominate your continent come the Industrial Age.