If the conductors were long enough and only the insulation was damaged, I would probably have put heat-shrink sleeving over the damage and avoided making joints. Good quality thick-wall sleeving can provide equivalent insulation to the original, although not all heat-shrink sold in electrical wholesalers is really up to the task. Tape is a bodge, although if carefully and correctly applied one can insulate things quite well with tape (it is an art that takes practice, not just slapping a few turns around.)
If the conductors were too short then I would extend with Wagos as you have done. In theory, the correct approach is to extend each conductor separately to the socket, but the length is so short that it makes a negligible difference to the resistance and won't cause any problems with testing, to make a tee joint with just one single conductor to the socket as shown in your pic. That reduces the total number of joints. One argument with a circuit that appears to be an unbranched radial is that there should not be any hidden branches in the CPC, so that a single test of CPC at the furthest point should run through all connections upstream and prove continuity throughout. Had this been the CPC, I would probably have been more specific to joint the two cables separately to reach the socket.
As mentioned by
@Lister1987, it's better to replace where possible. I would imagine that at least the cable to the socket above could be replaced within minutes, leaving just the inaccessible upstream leg to be jointed.
