It all depends on how you define "dayside" and "nightside", and how you define "entering" or "exiting" either one of them for a satellite.
I suppose a big part of the confusion comes from this statement:
Being in a polar orbit, Chandrayaan-2 enters the dayside of the Moon crossing the north pole, traverses through the dayside and enters the nightside ...
The degree of orbital shadowing experienced by an orbiting object with small orbital altitude is determined by its beta angle (normally used in reference to LEO objects but the concept applies to lunar orbiters as well).
The angle is taken between the satellite's orbital plane and the vector to the Sun. Depending on the value of the beta angle, a satellite ...
There is no circular orbit that has a share of 50:50 between night and day.
The possible times are a bit less than 50% to 0% night or, respectively, a bit more than 50% day to 100% day.
The two extreme cases are:
an orbit that is aligned with the terminator (the border between night and day on the surface) is in perpetual daylight.
an orbit that passes ...