I am a bit more black and white, and I think it is simple:
Cut and pasted a bit, the AIP says:
For other than an ATC route clearance in its entirety, and any amendments, only key elements of the following clearances, instructions, or information must be read back ensuring sufficient detail is included to indicate compliance: and then it lists B to G as per above.
That means, no readback of expectations.
That means no readbacks of radio report requirements like "report at 20nm DME or passing 6000ft" because this is not in the elements listed, it is not a radio frequency information: that would be "contact tower on 120.1" That is a frequency.
That means "clear visual approach" must be read back as it constitutes a route clearance (element a) and a an instruction on your level (element g) because it is a clearance to leave your altitude. And leaving that altitude requires a "left blah blah" call.
The opening sentance is a general statement about readbacks and is not the instruction, it simply introduces the instructions that follow, and because the information IS specificed so particularly, we can follow that.
I would argue that Darwin is incorrect IAW the AIP, but are you sure they are not using the Military ATC publications?