ezpublish: 
    # HttpCache settings, By default 'local' (Symfony HttpCache Proxy), by setting it to 'http' you can point it to Varnish
    # You may also set it to 'fastly' if you want to use the fastly CDN
    http_cache: 
        purge_type: '%purge_type%'

    # Repositories configuration, setup default repository to support solr if enabled
    repositories: 
        default: 
            storage: ~
            search: 
                engine: '%search_engine%'
                connection: default

    # Siteaccess configuration, with one siteaccess per default
    siteaccess: 
        list: [site, admin, test2, test3]
        groups: 
            site_group: [site, test2, test3]

            # WARNING: Do not remove or rename this group.
            # It's used to distinguish common siteaccesses from admin ones.
            # In case of multisite with multiple admin panels, remember to add any additional admin siteaccess to this group.
            admin_group: [admin]
        default_siteaccess: site
        match: 
            URIElement: 1

    # System settings, grouped by siteaccess and/or siteaccess group
    system: 
        site_group: 
            # Cache pool service, needs to be different per repository (database) on multi repository install.
            cache_service_name: '%cache_pool%'
            # These reflect the current installers, complete installation before you change them. For changing var_dir
            # it is recommended to install clean, then change setting before you start adding binary content, otherwise you'll
            # need to manually modify your database data to reflect this to avoid exceptions.
            var_dir: var/site
            # System languages. Note that by default, content, content types, and other data are in eng-GB locale,
            # so removing eng-GB from this list may lead to errors or content not being shown, unless you change
            # all eng-GB data to other locales first.
            languages: [eng-GB]
            content: 
              # As we by default enable EzSystemsPlatformHttpCacheBundle which is designed to expire all affected cache
              # on changes, and as error / redirects now have separate ttl, we easier allow ttl to be greatly increased
              default_ttl: '%httpcache_default_ttl%'
            # HttpCache purge server(s) setting, eg Varnish, for when ezpublish.http_cache.purge_type is set to 'http'.
            http_cache: 
                # If using fastly, 'purge_server' must be set to 'https://api.fastly.com'
                purge_servers: ['%purge_server%']
                fastly: 
                    service_id: '%fastly_service_id%'
                    key: '%fastly_key%'

        # WARNING: Do not remove or rename this group.
        admin_group: 
            cache_service_name: '%cache_pool%'
            var_dir: var/site
            languages: [eng-GB]
            content: 
                default_ttl: '%httpcache_default_ttl%'
            http_cache: 
                purge_servers: ['%purge_server%']
                fastly: 
                    service_id: '%fastly_service_id%'
                    key: '%fastly_key%'

        test2:
            languages: [pol-PL, eng-GB]
        test3:
            languages: [fra-FR, eng-GB]

$configResolver->getParameter('languages', null, 'test2')

[eng-GB, pol-PL]