There's a few things that have to be in place when adding a new Zabbix Proxy Host

1. Install a new server with the zabbix::proxy role
2. Add the IPv4 address of this server to profile::zabbix::agent::servers in the "correct" level of the hiera hierarchy. This might i.e be in a region-specific file
3. Add the new Zabbix Proxy in the Web UI. 
   1. Add to correct Proxy Group
   2. Enable active mode
   3. Configure PSK encryption. PSK Identiy and the PSK itself should be in hiera