Today, the supported model is to set up HA within the same cloud since it is a regional HA approach. If you want this across clouds you could easily just spin up a new one through automation in another cloud and restore the config backup. No change to data plane. 

To add to that, the Controller does not need to be up for continuity of your networking services. Gateways will keep routing their packets when the Controller is temporarily unavailable, the only thing is you will not be able to make any changes. Therefore multi cloud HA is overkill for most situations.

Regards,

Mark

Aviatrix controller is Agnostic but must not  be deployed in each of the CSP, what I meant is, you must not deploy four Aviatrix controller when dealing with four different CSP. Having deployed for instance in AWS an Aviatrix controller, you can scale out to other CSP such as Azure, GCP and OCI with AWS being the source. In other words, a single controller within a MCNA

Note: Aviatrix controller are built only in the control plane and not in the data plane, so no panic when it comes to availability and resiliency.