Can you try passing the numeric file ID with -file instead of the name, and the numeric import ID with -import instead of the name? You should be able to retrieve these by listing them with -files and -imports.
Great to hear that solution worked for you. You mark it as resolved.
In my case i was facing issue that script was on client server and without a proxy the Anaplan Connect API was not able to connect to Anaplan. We used the proxy specific to that system where script is stored and not the local machine.
If you are doing it on client server, they can provide you the same.