Side question: if the CP wins and Japan is the only successful Allies member, does the UK dare terminate the Anglo-Japanese Alliance?
The alliance with Japan was about containing Russia, the icing was countering German ambitions. With Russia gone, and Germany removed for now, Japan is a liability. Thus in OTL London could acquiesce to the USA, but here the USA is not an ally, indeed likely an antagonistic neutral barely harboring her ambitions or contempt. So once again Japan returns to value. I am on the fence if Germany would force through Tsingtao, Wilhelm loved it, it really is a prestige symbol for her victory, but Britain needs to keep Japan on side, not let Germany back in and get a peace in Europe more valuable than the piddles in Asia. AS loathe as Japan is to hand it back, Japan might already be eyeing Manchuria, that ups Japan's stake in China, a blow to London, but one they might find palatable in the heat of the moment. Taking a parallelism course, I say Japan takes Manchuria from Russia, Germany gets her lovely brewery back, and we set Asia up for some messy wrangles. Anglo-Japanese relations can break down later, the USA can nose in, Germany can align with China or if you really want to twist it, Japan, giving us a spooky collision course despite totally redoing Europe. Otherwise I think we screw China in TTL with too few ways to resurrect her.