I created an inbound email account, and set it to create case from E-mail.
The outgoing e-mail does not have any of the variables replaced like $acase_name etc. I edited the case creation template and tested again and it’s not sending the edited template, it’s still using the default template, which as far as I can tell doesn’t even exist in the system anymore because I edited it and renamed it so I’m not sure what’s going on.
There have been bugfixes recently regarding variable substitution… but since you forgot to say your SuiteCRM version I can’t say whether they apply to your version or not. You might want to search Github issues for it (including recently closed issues).
To clear up the mess regarding Templates I suggest having a look in your database to see which templates exist there.