"u:libvirt" produces the same error as "u:libvirt-qemu":
setfacl: Option -m: Invalid argument near character 3
I suspect the issues is the lack of a defined libvirt user in Fedora.
setfacl also accepts groups ... ie. g:libvirt, but perhaps that is something different altogether. Are you certain the focus of the command should be the "user" and not the "group"?
To check ownership or permission requests coming from the guest may be tricky, as the rights need to be modified just to add a file to the "shared" folder in Workstation. I understand that SELinux "permissive" mode logs all file requests. The log may offer a positive ID of the requesting user and/or group that holds rank in the guest system.
I will study-up on how to find and read the SELinux logs, and also, whether or not there is need to add a libvirt user to the Fedora host.