If anything, this undermines the argument by suggesting the aurora borealis may have occurred without any sunspot activity occurring five days before it.

This simply indicates that sunspots have occurred for many years. But it doesn’t help confirm John’s reported sighting of sunspots or connect the aurora borealis with confirmation of John’s sighting.

This strengthens by eliminating other potential causes of the aurora borealis. Only sunspot activity could have created an aurora borealis viewable in Korea, so there must have been sunspot activity before the Korean sighting.

This has no clear impact on John’s sighting. This simply gives more details about when his sighting would have occurred.

The fact John drew sunspots doesn’t help connect the Korean sighting of aurora borealis with John’s sighting of sunspots. What do drawings have to do with the aurora borealis? Nothing.