This is strange as I cannot reproduce it. After the same change and update I can see all users and I can create a new realm. Are you sure you haven’t done anything extra?
Anyway, this is an opensource project after all. You can clone it, modify cloudformation/aws-cloudformation.template.yml and create pull request. If you want to modify security group you can make changes in cloudformation/aws-cloudformation.template.yml. When your pull request is approved then openremote-cli will deploy new instances according to your needs.