I now finally have the German DVD of "Faces of Children", but I'm still unable to locate the BFI La kermesse hroque...
It must be somewhere, though. I'll report back if I watch any Feyder (and find the missing DVD so I can check the running time).

On the back of the German edition is a quote from Jean Mitry which goes something like this: "If I had to pick one film from the whole French filmproduction of the 20s I would definitely choose Faces of Children".