ScriptRunner to send email in types that do not support email template

I want to use a ScriptRunner Job to send email (for applicable issues) on regular interval.

But unlike Listener using Send Custom Email action, a Job does not support an email template.

While I can use SMTPMailServer.send() to send email in “Additional issue actions”, I will have to hardcode my email template and do string substitution.

Is there a cleaner way to do this?