Can you please elaborate what do you mean by touch area? Does it mean the potential areas on the PCB where the user may touch the board? If yes, it is better to cover them because the user may inject ESD into the chip through the open copper traces. This may damage the device. So it is always better to cover unused copper pads with insulator.
Hope this helps !
这个没有明显的区别，毕竟触摸动作需要透过盖板，不是手指直接触摸在Sensor Pad 上，所以铺不铺绿油对信号没有什么影响。