I found a solution that has work for me.
when you bring up the "trackpad handwriting" ctrl-shift-space,
1. Click "pause" on the lower left corner of the trackpad.
2. Click where you want to input the chinese character,
3. Click TOP Part of the Trackpad window where it says "Handwriting",
4. Click "click to resume handwriting",
if you click anyother spot, you will lose the curser, and you need to start over.
And you need to do these steps everytime - pause, place the curser, "handwriting", "resume".
it had worked for me every time. This is a strange bug, I think when you bring up the handwriting pad, it does not know where to insert the chinese character for some reason, even thought the curser is where you wanted it to be.