Whilst I do not condone leaving the cpc without a suitable means of termination or DIY installers how is a bit of insulation going to affect a 1.5 cable with a few downlights connected to it.I can't support someone doing something that they are out of their depth on as the OP has shown. Telling them it is ok to use flex and tuck it under the installation neatly is not an acceptable installation method and if if anyone working for me did that I'd let them go.
It's all ok tough as he has wrapped the cpc in a bit of insulation tape. Great job, not.