If you’ve no-arguments must have load-balanced autoscaling, and you can’t crack that calendar issue – I apologize but I was never able to duplicate it – then you might want to make your own full-stack variant. Full-stack provides all the necessary bits for operating clustered PHP – load-balancer, Redis session store, CouchDB document store, shared file system for non-PHI configuration data – but you could replace the Elastic Beanstalk with something else, perhaps a scaling cluster of containers. The openemr docker in the repo has a parameter, MANUAL_SETUP, specifically for a situation like this one where configuration has already been completed.
Edit: That said, you might not have the calendar issue anymore, since you can try EB 2.7.0 – or, if you want to see what breaks, roll the dice on upgrading your local beanstalk solution to PHP 7.1.