Hi
By design, there is only RG0 and RG1, RG1 is for the all interfaces and only this RG1 failover to the second firewall if one of the monitored interfaces were down.
But for sure the RG0 will failover too if the primary firewall powered-off.
"I noticed this lo0 behaviour during the failover tests"
So is this considered as an active-active!
By design its an Active-Passive.....
Regards