The limit on the celestial empire is quite necessary for the balance in the game, while I do not think the newest way is quite good at all, the expansion of China relied on the geography status in border region, it shall be hard for China to expand west out the Xizang and overcome the thrill of tropical climate. the worst is the restrict of supply line, which is the main reason why China did not expend west or south.
While, in EU world, the supply line did not exist so the nomad can be not powerful at all and so these huge countries own continents can exist, then we can think the nerf on Far East especially Ming is laughable.
If EU group would like to nerf huge powers, they shall not start from the poor Ming, it only has 1000 development, 50% local autonomy, 11 ducats per month and forever possibility of crush down, very low expansion possible. With the HRE system, it can be easy to turn these over 600 development into your vassal and make you the master of Europe, the austria wirh bohemia, low lands, eastern north Italy has over 1500 development, it is radigious at all. I never can believe these with 10 million people shall have the much higher development than those with 100 million people.
The real way of restricting huge op is to increase the difficulty to rule over a huge country for the distance from the capital and the difficulty to maintain a stable huge country.and this is the root reason why Chinese expansion is so slow,with the decay mililary, the Ming even did not conquer the Mongolian and Manchuria like what Russian did.
Please do not nerf the poor East Asia in science aspect, we have lost the prosperous economic and high development, the new nerf will make there a new New World like the Inca and Aztec.otherwise, the Far East should get strenghened in the province development aspect.