Hi,
When I read this I first thought you wanted to FTP the certificate file but you no, you want to assign the certificate on the FTP binding in IIS.
If the renewal failed the $result.IsSuccess will be False so you can wrap the whole thing in an If but I don’t see any disadvantage to setting the thumbprint anyway as it will still be the last valid value.
Our method for Test is basic and runs in the UI process under the current user so it’s not really a true test. Yes, more needs to be done there.