I too have found the wiring diagram disappointing, but Ive been trying to figure out the ground and bonding wire locations.
For the interior lighting, there's a bundle of wires running forward on the stbd side. IIRC, it reappears in the cupboard in the head, and splits up there. Some wires go forward for the bow lights, some stay there for the head and stbd salon lights, some manage to go up the mast (not sure where). I think the wires which power the vberth lights flip a U-turn back to the port salon light. The galley light has its own connection behind the fuse panel.
FWIW, wire on boats should be pre-tinned along its length, this prevents corrosion (which would cause the wires to burn out sooner) - this is why marine use wire is more expensive. Ive seen both in my boat, the regular wire just comes apart.
Hope this helps. A report of your findings would be appreciated.
Best of luck!