The overview speaks of a "here's my key!" / "you are registered!" step that letsencrypt-nosudo doesn't seem to have. It seems that your first communication with the CA is during step 2 (requesting challenges). Does this affect your script's ability to do things like subject alternative names?
This script takes certificate signing requests (CSR) as input. If you want a subject alternative name, it's up to you to add that to your CSR file before you run the script.
The official Let's Encrypt client is mostly focused on ease of use. This script is mostly focused on not knowing your secrets or requiring privileged access, and it assumes you know what a CSR is and how to install a signed certificate on your webserver.
