So the real question becomes whether China can keep Yunnan on J2 as well, and how it affects Japan going forward.
Certainly being able to buy artillery seems worthwhile, though less useful when simply trying to stack Yunnan (art over inf means 1 less unit each on C1 and C2) but necessary to counter Japan’s relatively weak ground forces.
It looks like it sort of depends on Japan’s J1. Yyou can keep Yunnan on J2 but if Japan brings an additional transport (or 2) on J1 so they can help attack on J2, China needs some or all of UKPac or Russia’s air force to save the 15-20 inf/art
Of course, if Japan is using transports to feed the mainland, it means less income down South.
So something like this strategy might be hell on Japan if the U.S. is aggressive on the Pacific side. 9ish less ipcs on J3 is one less ship to defend, and tends to ripple through the early choices.