Good troubleshooting.
I agree! Using a standard root node name offers many benefits including letting you change filenames as you wish. This was a deliberate change and you can read more in the release notes for XLSForm Online v2.0.0. The documentation for the setting called name
which lets you set the XML root node name is available here. Please try that with XLSForm Online v2.x and let us know if you run into any other issues.