The German army was very well-equipped and versatile compared to most armies at the time. This was first into public knowledge when Germany sent volunteers to the Spanish Civil War, where they achieved brilliant success. While yes, Soviet volunteers would be more numerous, a few German panzers would really benefit the Chinese struggle against Japan, in case Germany is more sympathetic to China.
You're not wrong, but you're missing my point: I'm not asking what difference would the German aid make to China- possibly, as you say, quite a lot- I'm asking what difference German aid would make to Western perceptions of China.
There was a contention that continued German aid to the nationalists would push the West on to Japan's side- I was pointing out that the Chinese were already being supplied by a nation the west considered to be an Axis ally, and not only did it not change Western opinions about China, the UK and US continued to provide their own support.