Explanation
The Cisco HyperFlex Edge invisible cloud witness is only required for 2-node HX Edge deployments.
correct, it has to connect to Intersight as it is a CLOUD invisible witness as per the document shared:
The Cisco HyperFlexEdge invisiblecloud witnessis only requiredfor 2-nodeHX Edge deployments. The witness does not require any additional infrastructure, setup, configuration, backup, patching ,or management of any kind. This feature is automatically configured as part of a 2-node Hyper Flex Edge installation. Outbound access at the remote site must be present for connectivity to Intersight (eitherIntersight.com or to the Intersight Virtual Appliance). HyperFlexEdge 2-nodeclusters cannot operate without this connectivity in place
https://www.cisco.com/c/en/us/td/docs/hyperconverged_systems/HyperFlex_HX_DataPlatformSoftware/ Edge_Deployment_Guide/b_HyperFlex_Edge_Deployment_Guide_4_0.pdf

Explanation
https://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus5000/sw/system_management/503_n1_1/ cisco_n5k_system_mgmt_cg_rel_503_n1_1_chapter11.pdf
https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.cisco.com/c/en/us/td/docs/switches/ datacenter/nexus5000/sw/system_management/503_n1_1/ cisco_n5k_system_mgmt_cg_rel_503_n1_1_chapter11.pdf&ved=2ahUKEwjQ8ubTuK3xAhWm3jgGHZ9gB
0oQFjAAegQIBRAC&usg=AOvVaw2j0nnvXiChAoVooxX2Qx0g

Explanation
Logical configuration-An XML file that includes all logical configuration settings such as service profiles, VLANs, VSANs, pools, and policies. You can use the file generated from this backup to import these configuration settings to the original fabric interconnect or to a different fabric interconnect. You cannot use this file for a system restore.