[russianGuy83829]

This doesn't address the coincidences that the GRU unit is consistently at the place where the "headaches" happen, get identified by the victims, and work with one of the only people (Russian professor) researching the rare disease that was diagnosed for one of the victims. There are documents in the article that link the group with the researcher, which explicitly mentions acoustic non-lethal attacks.

[pas]

There were ~1000 cases reviewed, and these GRU gremlins were only at a few places, no?

So most likely is that there are a few true positives, and the vast majority of them are false positives. (And of course good luck telling this to anyone who works next to someone who just met a GRU operative, or works in a high-stress job and regularly feels that there are people out to get them.)