This is something I've been batting around implementation ideas on for a little while now. There's a ton of variability provider-to-provider to account for on automating some of it, so I was leaning toward more capable cluster managers that are already available off the shelf. Easily the most capable is Kubernetes, but it comes with a lot of added complexity. It's distinctly possible based on the way Cloudron works to entertain some of this stuff, and I've been sketching out a number of different ideas. Nothing is formally roadmapped afaik right now.
That said, it would be helpful in thinking about options what you see as the changes in your experience that these sorts of ideas would enable. Adding an additional node, which seems to be what 3 of your 5 ideas are focused on (load balancing, hot stand-by, and auto-scaling), may or may not be the best approach to minimize downtime depending on how the "normal" use would pan out. It's already not all that difficult to keep an alternate machine restored from backups as a standby, but given the way the system handles app-level failures, it's hard to say in what cases that would be useful; there's added difficulty in reversing that failover and keeping it real-time.
Ultimately, what probably does make the most sense to close the gap on those goals while not messing too much with the underlying architecture and existing packaging is some sort of coordinated cluster manager that keeps the single-container approach but allows the system to reallocate those app containers across k different servers. Something short of Kubernetes could achieve this pretty easily, but will need a lot of work to pull off. For these reasons, I've started looking more at Hashicorp's Nomad as a potential solution to the cluster management side of things, but I'm still in the very early stages of what a Cloudron implementation would look like. At its full potential, this could enable things like multi-region and even multi-provider deployments. Ideally, the details of managing this would be hidden away behind the Cloudron interface, but I've not even yet begun to start spiking out an actual implementation.
I'd love some more thoughts and feedback on the approach generally though!