I would look at the grounding wires for the headlamps - usually one for each side.
The connections can be corroded, loose or even the wires broken given the age.
Based on some of the issues you mention then that is a possible cause that I have seen before.
The duplication, or more, of points in distributors was to avoid contact bounce.
The coil really needs a single change of state “closed to open” to generate the spark and as rpm rises the number of contacts needed causes the contacts to bounce open as they close changing the current flow through the coil.
Having 2 sets halves the number of close/open each ...
Could this have done damage to the bike?
One thing that can happen on all engines having multiple cylinders and a catalytic converter is this:
N-1 cylinders are firing, providing hot exhaust to the catalytic converter
The remaining cylinder is not firing, so the raw evaporated fuel goes to the catalytic converter
The fuel burns in the catalytic converter ...
It's possible that the testing OBD system could cause damage to the car's systems, but it's very unlikely. The reader could have sent a surge of power to the ECU, which is the engine's brain, but that would probably have shorted it out and it wouldn't even start up. That's not to say that the mechanic couldn't have damaged something and caused your problem, ...
A broken earth or ground cable somewhere.
Perhaps between battery & chassis or battery & body or body to chassis.
Some are small and across the gearbox mount.
While the cable may look good as the insulation is not broken the conductors can be broken or corroded.