Concerning the 0.01?F caps:
This part of the circuit is to create the glissando from the portamento: the low-pass filter just smooth the steps of the glissando to produce the portamento. It is explained on pages 24-25 of the CS-Series servicing guide.
Depending on the Portamento Short-Long slider position, two values of the resistor are used, whereas at least in theory, the resistor value should vary continuously with the slider. So resistors are already approximations and certainly a precise value of the capacitor is not that important.
The change of the value of the caps was probably a last minute improvement. If the portamento sounds good at any position of the Short-Long slider, the value of the capacitor is certainly correct.
