The firmware of the device is limited. At this price point one could not have as many features as one might like. As it was, the features included were sharply pushing the state of the art for a device in the cost range.
What I have been doing to compensate is to simply remap the CC values to polyphonic AT messages in software, and this works a treat.
I also remap the messages to have better responsiveness characteristics, though this does lose some of the value resolution. I agree it would be nice to have this built in, or greater than 7 bit z-axis resolution, but my workaround is not too bad.
I found that monophonic aftertouch was not very useful, so I don't recommend you continue to pursue that direction, though of course it is up to you.