I know that Germany loved their captured tanks during the World Wars. During WW2, they seemed to use whatever they could get their hands on, even though they had a robust domestic tank program. Looking at WW1, however, Germany struggled to produce many tanks at all and used mostly captured vehicles, but I've only been able to find examples of British tanks being used in this role.
Was there some reason, logistical or doctrinal or else, that captured French tanks don't seem to have been used, even though they were a more numerous adversary? Is this just a bias of available photographs and accounts?
I bookmarked this post back when you made it and have been holding off on responding to it in the hopes that lockdown might be eased so I could access better sources, but that doesn't look like it's about to happen and I figure part of an answer is better than none at all.
All I can tell you I'm afraid is that while I don't know if any captured French tanks were used by the Imperial German Army, I doubt they were. All the sources I could get my hands on were secondary sources citing secondary sources, but when making reference to German tank forces they explicitly mention either detachments of purely the A7V German produced tank or British tanks, with no mention of French vehicles. It’s also worth remembering that while there are different accounts of the actual number of tanks built and refurbished by the Germans they all are rather low and there wouldn't be much room for a detachment of captured French tanks to hide. Alexander Watson is probably the leading military historian of the Central Powers and he cites only 75 captured tanks being pressed into German service.
As for the reason why I am afraid I simply can't give you an answer with the sources I have available, but the German military continually failed to give the tank much credence a weapon and I suspect that played a part.
You might be in a country which isn't struggling as much with the pandemic or just closer to a good library, so if you want to do some research of your own the sources I really wanted to get my hands on but couldn't were,
Hundleby, Maxwell, and Rainer Strasheim, The German A7V Tank and the Captured British Mark IV Tanks of World War I (Sparkford; Newbury Park: Haynes Publications, 1990)
Koch, Fred, Beutepanzer Im Ersten Weltkrieg: Britische, Französische Und Russische Kampf- Und Panzerwagen Im Deutschen Heer (Wölfersheim-Berstadt: Podzun-Pallas, 1994)
Searle, Alaric, ed., Genesis, Employment, Aftermath: First World War Tanks and the New Warfare, 1900-1945, Modern Military History, 1 (Solihull: Helion & Company Limited, 2015)
Sources Cited
Beach, Jim, ‘British Intelligence and German Tanks, 1916—1918’, War in History, 14.4 (2007), pp. 454–75.
Raths, Ralf, ‘German Tank Production and Armoured Warfare, 1916–18’, War & Society, 30.1 (2011), pp. 24–47.
Watson, Alexander, Ring of Steel: Germany and Austria-Hungary at War, 1914-1918 (UK: Penguin Books, 2015)