You don’t need multiple subsomains and multiple containers for this, both es. and en. are subdomains for the same top-level, making it so that both share 1st party context.
Your setup should be a single subdomain like ss.example.com, which both en. and es. sites would use as a server_container_url.
You need a business plan if your plan to use multiple tracking subdomains, and point those to your Stape instance. In your case this seems redundant because all the subdomains of your top-level can report via a single tracking subdomain.