CVT transmission slipping

I have a Toyota vitz 2007 and I am facing a problem for about 2 weeks now. Sometimes when I press the accelerator, the engine revs up but I hardly see any acceleration.

The problem is severe when I am going uphill. If I stopped midway on the slope and then tried to accelerate, the vehicle almost doesn’t move. If I press the accelerator harder, the vehicle starts to jerk, but still hardly moves.

I have a problem with my wiring harness too, and I have soldered several broken wires. Mostly due to the harness, vehicle idles roughly.

I posted the this question few days back, but I wrongly mentioned that my transmission is automatic, but only today I found that it is CVT.

I took the car to a mechanic and he is going to disassemble the gear box and check tomorrow.

Would it be better to first change the wiring harness and see?

Can CVT transmission slip? Could this be a problem with the torque converter?