Thank you for your reply, dear fandaL. Fortunately, I was able to resolve the issue. My hand-written inp file is fed into calculix on a Windows computer. There I got a different error, which later turned out to be related to the Node coordinates. There seems to be a limit of 13 digits on them. The code runs perfectly when I use "[:.13E]".format(X) in my Freecad script.
Best,
Aida