Hi Micoom,
There were several inter-related tweaks that we made in this game do to using the 'event driven' entry rules for the US that we wanted to try out. Most of them worked I believe.
I think giving China the ability to build artillery and AA as well as move outside of China is a bit too much. I think an appropriate adjustment might be to start them with an artillery and an AA gun (which they cannot replace) and still not let them move out of China.
I know a couple Chinese divisions operated in Burma during the war - but it was pretty limited. Chiang wanted to conserve as much of his army as he could for the big fight with Mao. If folks really wanted to let the Chinese move outside of China, I think it would have to be something like 3 units maximum or something.
The other thing we did, was to say that all of the Japanese units that start in Manchuria are frozen in Manchuria until the Russian garrison restrictions are lifted. So that made the Japanese in China a little weaker too.