That's an odd error. Are you using R28 or did you build the development version?

I just realised, even better would be for Emperors and Empresses (only) to upgrade to using an Imperial Carriage (which would be kind of slow). Some of its characteristics, taken from Records of the Grand Historian: "I have always been told that only the most distinguished men of the empire are privileged to ride with the Son of Heaven in his six-foot carriage", "Your Majesty proposes to gallop down a steep slope in a carriage drawn by six horses", "He then began to ride about in a carriage with a yellow top, decorated with plumes on the left side, and to call his orders “edicts” in imitation of the Han emperor, all of which was intended to show that he was an equal of the ruler of China".

I didn't pay attention to that part, but for Han Xin an obvious upgrade could be "Marquis of Huaiyin" then. For Emperor Wu you can't really go higher (and strictly, it's a mistake to use that, since that's the posthumous title, but whatever, it would be a headache otherwise), so I guess a mount would be fine, but, although a horse and hunting enthusiast, he probably never rode to battle (maybe Expansionism should be a Global Aura, and Builder a Ranged Aura instead, to keep him more "domestic", in opposition to others like Han Xin). And, although I'm not really focusing on the Han right now (still at least 600 pages to go for the Athenians, as I've said, things I do to myself), an obvious Unique Tech (or even Unique Building?) for the Han should be the Blast Furnace ("The oldest extant blast furnaces were built during the Han Dynasty", whose effectiveness was enhanced by Du Shi in 31 AD using bellows operated by waterwheels, helping mass produce cast iron, which was already known in China, but unknown in Europe until Medieval times). It could speed up Forge techs and soldier recruitment. Since they are "most efficient at a somewhat larger scale of production", maybe some cumulative effect could be considered in case of making it a Unique Building (https://www.scribd.com/document/248548406/2-Iron-Making, https://donwagner.dk/EARFE/EARFE.html).

This is strange, I can't figure out why. As for the code, I can't help you; you can contact the programmers on the forum or @Stan`

Also, please take a look at this log too:   ERROR: JavaScript error: simulation/components/UnitAI.js line 4253 Script value conversion check failed: v.isNumber() (got type Array) ERROR: Script message handler OnOwnershipChanged failed ERROR: JavaScript error: simulation/components/BuildingAI.js line 139 Script value conversion check failed: v.isNumber() (got type Array) ERROR: Script message handler OnOwnershipChanged failed ERROR: JavaScript error: simulation/components/UnitAI.js line 4253 Script value conversion check failed: v.isNumber() (got type Array) ERROR: Script message handler OnOwnershipChanged failed ERROR: JavaScript error: simulation/components/UnitAI.js line 4253 Script value conversion check failed: v.isNumber() (got type Array) ERROR: Script message handler OnOwnershipChanged failed GAME STARTED, ALL INIT COMPLETE 08:50:06: Debug: window wxMenuBar@0x5625bf50fdf0 ("menubar") lost focus even though it didn't have it ERROR: JavaScript error: simulation/components/BuildingAI.js line 139 Script value conversion check failed: v.isNumber() (got type Array) ERROR: Script message handler OnOwnershipChanged failed ERROR: JavaScript error: simulation/components/BuildingAI.js line 139 Script value conversion check failed: v.isNumber() (got type Array) ERROR: Script message handler OnOwnershipChanged failed ERROR: JavaScript error: simulation/components/BuildingAI.js line 139 Script value conversion check failed: v.isNumber() (got type Array) ERROR: Script message handler OnOwnershipChanged failed ERROR: JavaScript error: simulation/components/BuildingAI.js line 139 Script value conversion check failed: v.isNumber() (got type Array) ERROR: Script message handler OnOwnershipChanged failed ERROR: JavaScript error: simulation/components/BuildingAI.js line 139 Script value conversion check failed: v.isNumber() (got type Array) ERROR: Script message handler OnOwnershipChanged failed ERROR: JavaScript error: simulation/components/BuildingAI.js line 139 Script value conversion check failed: v.isNumber() (got type Array) ERROR: Script message handler OnOwnershipChanged failed ERROR: JavaScript error: simulation/components/BuildingAI.js line 139 Script value conversion check failed: v.isNumber() (got type Array) ERROR: Script message handler OnOwnershipChanged failed GAME STARTED, ALL INIT COMPLETE 08:52:51: Debug: window wxMenuBar@0x5625bf50fdf0 ("menubar") lost focus even though it didn't have it