Another thing you could do for the Chinese fighter if you would prefer it to be the same color as the Chinese troops is get one from Historical Board Gaming. They have these Allied Supplement sets in several different colors. One of them is called Celery Green which is the same color as the British pieces in old copies of Revised. This color is very close to the same color as the Chinese infantry pieces. The Allied supplement sets include P-40 fighter planes. You don’t even have to get the entire set because HBG sells these pieces individually. You can pick up 2 or 3 P-40s and there you go! Your very own Chinese fighter unit.
As for Artillery, HBG also has these Neutral sets in several colors and one of them is a yellow-green color. That color is a little brighter than the Chinese infantry, but it works okay with them and certainly is different from the US artillery. The Neutral sets have an artillery piece called a “75 Veld” which I think is Polish or Belgian but works fine for Chinese since they mostly had older stuff anyway.