BIK_116.80, to quote part of what you wrote
“(a) Time above overcast or at night in Visual Meteorological Conditions (VMC) is not counted as instrument flight unless there are insufficient external visual cues (including a useable natural horizon) to fly the aircraft – refer CAR 2 definition of ‘instrument flight time’”
I suggest that the Australian regulations require that you must log as instrument flight time any time during which :
* you are the pilot flying; and,
* you are in IMC; or, there are insufficient external visual cues to fly the aircraft (eg dark night with no useable horizon, or between layers of cloud with no useable horizon); or, you are "under the hood";
We do a lot of Night VFR flying in VMC where there is no or very little visual horizon. Are you suggesting that is not legal (I.e. no clouds and no moon). The way I read it, we log IF time if we are on an IFR flight plan, in cloud or under the hood or if we are VFR (night or day) only if we are under the hood.
Perhaps with the rules being re written CASA might find clearer words to describe what they mean.