Given the history, with the Great Seal Bug
https://en.m.wikipedia.org/wiki/The_Thing_(listening_device)
I would expect plenty of monitoring; it is cheap and easy.
But maybe I'm just expecting too much vigilance here.
On the other hand a fine, grounded mesh will protect just fine against such attacks. Even in windows. Look up IEMI shielding.
Now taking these two together I think that it is possible that the embassy had both shielding and detectors. Because the attacks may have happened outside the shielding, and the detectors were inside to detect bugs.
Re: a mesh in the windows, given that we can’t even shield microwaves, I’m seriously doubting such a weak faraday mesh would be effective. But I don’t really know what the attenuation model would be.
Perhaps my assessment is overly pessimistic, but I think your assessment is overly optimistic.
2. This Vanity Fair article believes it's mass hysteria: https://www.vanityfair.com/news/2019/01/the-real-story-behin...
https://en.m.wikipedia.org/wiki/The_Thing_(listening_device)