I just renamed a Cluster we use for Testing, just for giggles and it worked.
I went into the Corosync file and changed the cluster_name.
/etc/pve/corosync.conf
Old-Name: pve-frg-tk
totem {
cluster_name: pve-frg-tk
config_version: 11...
FYI:
We have tested it on our Test Custer for a wile, with HA and all basic features. We didn't experiences any issues.
But still be careful, it may still have a Issue that we didn't found!