C1/C2 and R2 form a low pass filter. Ignoring the diodes, if a fast edge is applied to to cTXDRV-PWEN then the voltage across C1/C2 (and therefore the base/emitter of the NPN transistor) will be an inverse exponential rise with time, slowing down the turn on (or off) of the transistor.
With the diodes in place, when the voltage across R2 exceeds about +-0.3v (schottky diode) one of the diodes will conduct and pass more current into C1/C2 increasing the rate of change of voltage and speeding up the switch on of the transistor. When the capacitors have completed charging (or discharging) there will be no voltage drop across R2, and the diodes will be turned off. In this state any noise up to the +-0.3v threshold will be filtered by R2 and C1/C2.