There is currently a limitation with SMS and email notification templates where we cannot retrieve them to be translated until they've been edited from the default. This is noted in Shopify translation API limitations Here. If you can not find any templates in the App, then this could be reason. You can edit the templates from your Shopify admin, the edit could be very superficial, such as adding a space. After that, you can manually trigger a "Sync Items" scan. You should see the templates after the scan is completed.
Due to a Shopify limitation, only order has language info, so Shopify can only send order related email in other languages.
For example, any user account email template such as account creation or password reset is not translatable. Shopify is aware of the issue and as soon as these types of email templates are translatable, you will be able to translate them in our app.