Recently discovered that you can actually use nested Mapping during experiments. As I am not familiar with CloudFormation, you may need to check the example by yourself.
Check out "VersionMap" in https://github.com/ppatram/gcp/blob/c03f1a94503971e91531f8bf3bfd09374ecb3256/dhal/AWS/CloudFormation/al2-mutable-public.yaml