The change would not be very small as to make it general we would need to make cumin support multiple instances of each backend, each one with their own settings and also a way to select them via the query language. Definitely a breaking change for the existing config and query language.

As a temporary and also a bit unpleasant workaround you could have puppet generate multiple cumin configuration files and use a different file based on the cluster you want to work on. Ditto for spicerack setting the instance_params's cumin_config to the different ones. That would require though to run cookbooks with the -c/--config-file flag.

I just discovered that we do have dedicated Cumin instances for tools and toolsbeta, where /etc/cumin/config.yaml points to the respective puppetdb instead of the production one:

fnegri@tools-cumin-1:~$ sudo cat /etc/cumin/config.yaml
puppetdb:
    host: tools-puppetdb-2.tools.eqiad1.wikimedia.cloud

So you can make queries such as:

fnegri@tools-cumin-1:~$ sudo cumin 'P{O:wmcs::db::toolsdb}'
2 hosts will be targeted:
tools-db-[1,3].tools.eqiad1.wikimedia.cloud