A friend mentioned how terrible most cold email generators are at actually generating natural feeling emails. It just took asking him questions about how actual people in marketing come up with emails to come up with a chain of thought that produces intentionally uncanny emails for a wide range of inputs: https://rentry.co/54hbz
It's not like you can't technically fit what I described into bunch of comments (or an obnoxiously long multiline comment), but it'd be bulky and not conducive to general happiness of anyone involved.
I much prefer repurposing Nunjucks templates to keep all of that a separate document that's easy to manage with version control