There has been no change in what people can and can't do for years, in the main it is covered by case law, for example
the Emma Shaw case. What is a problem and this has not changed in years is how to show some one has the skill required, I would have thought that pushing a button and writing down what the meter says is easy enough and no reason why a semi-skilled electricians mate should not do that task, and if there was some odd reading then clearly it would required some one skilled to investigate further.
However that was not what the court ruled, they found the foreman guilty as he had used semi-skilled labour.
So how can one define "having the technical knowledge or sufficient experience to enable him/her to avoid dangers which electricity may create." if you don't have it, then likely you will not realise you don't have it, so only way is for some one who does have it to test you in some way to see if you do have the knowledge.
Be is a radio ham exam, or showing you can read the regulations, in real terms you need some thing to show both you and others you have some knowledge. I would say with items like lighting track plugging in a new lamp is not different to plugging in a desk lamp. But if something goes wrong, will insurance pay out, and will the HSE agree with what I have said, and if not what will a court say?
As to qualified electrician, really no such beast, we all have our areas of expertise, I was back in the 70's a qualified electrician, I had papers to show it, however if you read the paper it actually said I was an auto electrician who do work with vehicles like the electo-haul with high voltages way above those normally found in factories and houses, but I was never taught the regulations, and when I moved to industrial electrics I found it easy to break the regulations even if I could get things running.
So by the 80's I was working on poly-phase and industrial items classed as low voltage (under 1000 volt AC) mainly abroad, and as a result all my employer wanted was for me to get the plant working, no one really worried about what bits of paper said, then the 16th edition wiring regulations came out, and for the first time people started to quote regulations and actually take exams to show they could read the book, I think I held out until around 2001 when BS 7671:2001 issued, June 2001 was considered as being the 17th edition in all but name, and I took a series of exams to show I could read, in 2008 had to do it again, and really I should get it done yet again as now BS 7671:2018 but not bothered as retired. But by 2001 we were finding people actually wanted to see written qualifications, and after the Emma Shaw case people were getting really nervous about asking anyone to do work which you can't show your trained to do.
But it is the silly things that catches one out, I was working on a bottling plant, it was controlled by a PLC but we did not have labels on the program, so I had the E-Stop in so nothing would run, and was activating each sensor and writing on the program a name so identified, lucky it did not get me, but it seems no one had considered air was power, so I activated one sensor and a air motor started to spin, now I knew there should be an air dump valve, so I did a temporary fix altering the PLC program, and wrote a memo to boss saying it needed a dump valve, but unless one knows the rules one would simply not know the alteration to PLC program was not enough.
And that is where the training comes in, you can't work out things like that, you need to have read it, or been told it.