Nice to see other interesting instruments available. But with this the amount of samples is far too low. If I was intelligent enough to put out an app like this, I would make sure the amount of sampled areas recorded would correspond to the complexity of the instrument. For example; I would have a minimum of 64 surface areas sampled. Each surface area should be sampled a minimum of 6 times for each attack level, I.e. soft,moderate,hard,aggressive.
The software should plot these points on the surface and respond to the area tapped, the attack level and run through the cycle of recorded attack levels in a random fashion.
Since, I do not write apps, I have no ideas of the possible granularity supported by the operating system.
Good luck.