Paul Tomblin via Mailman-users writes:
Like I said, there’s no templates listed in the UI.
Ah, I read that as "no relevant templates".
The migration from Mailman 2 doesn't need a working Postorius, so it doesn't use the same mechanism as the UI. It should write to a parallel tree under the $mailman_home/$var/templates directory. The fallback tree is in site-packages/mailman/templates, and otherwise they have the same layout. Since you're not seeing anything in the other lists, the migrated tree is probably very sparse; tab completion in the shell will probably take you straight to the relevant directory.
$mailman_home is where you installed Mailman, or wherever your distro package installed it. Most likely $var = "var", and if not you can probably find it in your mailman.cfg (or just use "find $mailman_home -name var").
Steve
-- GNU Mailman consultant (installation, migration, customization) Sirius Open Source https://www.siriusopensource.com/ Software systems consulting in Europe, North America, and Japan