Oh did he now...off with his head! 🙂
With the sdk:
>>> fqdn['tmName'] = 'node.test.local'
>>> node = b.tm.ltm.nodes.node.create(name='node.test.local', address='any6', partition='Common', fqdn=fqdn)
The key for you is to not supply every argument that you see on a GET. Just setting the object name, the address, and the fqdn is sufficient, so if you clean up your code to reflect that it should work just fine. Supplying the autopopulate or addressFamily attributes in the fqdn dictionary will fail on POST.
I contribute to the SDK as I have time, but the larger team working on it strive to make it easier on the end users. My $.02.