Not true. Now a days mostly Flt Lt. are flying. The newer lot will increase more after creation of third sqn.
Night strike capability is not demonstrated yet, but as Oscar said its something which is already there. Senior pilots evaluated it during night sometime ago.
For night interception you need pilot with good understanding and knowledge about reading information from sensors during night. Lights in the cockpit create problems during Hi-G maneuvering and may lead to disorientation. [that the answer to your main question regarding thunder's night missions...PAF is playing it safe and slow
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NVG capability and FLIR are required for night strike missions. Flying low and fast during night especially in a high threat environment makes FLIR a MUST requirement. JF-17 can rely on C-802 for night strike or BlueSky Nav pod.