The biggest concern I see for you is scale. Given that you mention hosting quite a number of domain names, I don't think my software would be the most appropriate for your purposes. You really need a more scalable solution. The plugin you purchased may allow that. I probably sounded the alarm too quickly. I reacted mainly based on the questionable domain name (letsencrypt-for-cpanel.com), which I'm fairly certain violates trademarks for both Let's Encrypt and cPanel.
Are you guys alright with that website's name?