I've loaded higher quality pictures of this article, making it much easier to read. I've also added a bunch of notes for people to consider.
With Haller in hand, I've been reviewing all the material relating to the Girandoni and might as well start with the first (in English anyways)
It didn't take long to realize that it wasn't at Wagram where the Austrians used air guns. Instead it would have been the 1809 Tyrolean Revolution where Tyroleans used their own personal airguns against the French in what amounted to a guerilla war. That the Tyroleans would have had and used air guns against the French is easy to assume. Particulary, when it is known that it was the Tyrolean Sharpshooters units that were equipped with the M-1780 Girandoni in 1793-1796. Which means that there would almostly certainly have been Tyrolean Sharpshooter (Girandoni) veterans taking part in the popular uprising.
I suspect that there were communications between Marshall Lefebre and Napoleon about Tyrolean's using air guns. Would Napoleon have ordered air gunners put to death? Of course he would have. Doubt Lefebre would even have needed an order to do so.
In his 1973 rebutal "Napoleon was Not Afraid of It" Baer points to his source for his 1955 article as K. Maleyka published in Berlin 1937. It would be very interesting if a copy of K. Maleyka, Berlin, 1937 could be obtained. It certainly goes onto the Resources Needed list.