Interesting piece. I had to look up the gun that it went to. Seems to be an at gun that was behind the times and struggled with german armor in 1940. Could have sworn that germany was primarily using pz2 and czech 38t at the time right?
The most common German tanks in 1940 were still the Panzer 1 and 2, followed closely by the Pz38t. The Hotchkiss 25mm had no problem with the frontal armour on the Pz1 and 2, and would just need close-ish ranges for the Pz38t, Panzer III, and Panzer IV, as it could penetrate 40mm of armour at 400m, and about 50mm at 100m. Meaning, effectively, at 400m it could go through the armour of any German tank of the time (the thickest armour would be the Panzer III and IV, with 30mm fronts).
The main weakness of the Hotchkiss was simply the size of the round, which was unable to cause major damage to the tank, it being effectively a highly up-gunned AT rifle. This meant that, while you could kill the crew, the tank itself would not be badly harmed, and so was very easy to simply patch the hole and send it back into the field with a new crew. It is similar to the state of affairs in the Polish campaign- the Poles knocking out almost 75% of the German tank force (1400 tanks claimed, which matches quite well with German records), but on roughly 40% of those, the Germans were simply able to weld over the AT rifle hole and get the tank sent back into the fight. This plays hell with post-war accounts, as the Germans listed field-repairable and/or factory repairable tanks as merely 'damaged', meaning the number of German tanks listed as 'destroyed' (ie, unrepairable) was a much smaller number than the actual number knocked out in combat. The only real way to calculate German tank losses is to look at divisional records showing actual tank-on-hand numbers, which is how you'll find things like the 4th Panzer in Poland starting the war with 352 tanks, and being sent home to Germany on September 18th/19th with ~90.
To add to this, the Germans had similar troubles with the 37mm. I remember one account where a British tanker in France in 1940 caught a 37mm shell through his tank that entered one side of the turret and went out the other cleanly, without hurting anyone or anything. He simply stuffed a sock (yes, a sock) in each of the holes and went on with his day.