Mention Trojka and the clouds of suspicion start to darken....
Just to be clear, does he show the MG34s as a single quad mount? I have a few books on German armored trains, but I don't see any photos of this configuration, although I have only a few photos of this type of train. Most other trains show a dual mounted MG34 for AA defense as being common.
A quad mount isn't that odd, but I understand your desire to find actual proof of it's use on this particular train.
I recently found this photo of a Hungarian commander with 10 Broom-Handle Mausers mounted for AA defense. 
I'd like to see him trying to reload this awkward arrangement. 
