So we can now make a few guesses as to what the elusive China number mechanic was from the last DD. Seems likely that is a counter for this new Mandate. Oddly enough, in the screens it seems Britain is halfway to having fulfilled the objective though, being either Emperor of China or having atleast 50 Mandate.
But Emperor of China is new aswell. Does it simply refer to the tag that uses the Celestial Empire government type? Or is it something new entirely? The way it seems to be constructed, being an Age objective and all, would suggest that it's a title that is easier to usurp than before. There's a reason it's one of the objectives and the Manchu are one of the nations given a specific bonus for this age. And it looks to be a military bonus aswell, to help them in their conquests.
My guess is that this new Mandate mechanic is a combination of some of the ideas that I and a few others suggested in one of the China threads in the EUIV forum. That means a HRE-like system, with Mandate instead of Imperial Authority, but without China being divided into several independent tags. Mandate either gives bonii or malii depending on its level, or it allows the current emperor to do certain things like in the HRE. Low Mandate would presumably allow other tags in the Chinese tech group to claim the Emperorship, giving unique CB's and so on. I'd guess low Mandate also increases revolt risk and separatism and so on, thus being more likely to cause an implosion. The system then helps one of the tags in the area claim and conquer China so that a new Empire can arise instead of the current situation, where China usually implodes and then either stays imploded or Ming reconquers its cores one bit at a time.
I'm thinking the Banners alluded to here is a unique mechanic exclusive to the Manchu to give them enough manpower to conquer China. The Manchus didn't only have the Eight Banners, but also the Green Standard, which was made up of foreigners (read: Han Chinese) that fought for them. So perhaps the game system is a sort-of inverse of the Condottiere system, where Manchu are able to draw foreign manpower up to a certain size to field in their armies.