How to localize E-commerce email templates

Yes it is. Email templates allow macros to be used, so you can put in resource macros in:

{$ My.ResourceString $}

https://docs.kentico.com/k11/e-commerce-features/managing-your-store/maintaining-multilingual-stores#Maintainingmultilingualstores-Maintainingmultilingualtexts

For the Email To based on culture, i would recommend making a custom Macro Method and set that as the Email To, it's untested but should work.

Email To: {% Util.GetEcommerceEmailTo(CultureContext.CurrentCulture) %} (something like that)

Check documentation on how to create custom macro methods.

If the contents are totally written in different langanges, I would preferred to customise order info provider and shopping cart info provider to override template CodeName in different langauages for notification.

(e.g. preset the email templates Ecommerce.OrderNotificationToCustomer.EN_US Ecommerce.OrderNotificationToCustomer.FR_CA, according to current culture context or current user preferred culture, the custom provide override function handle to override the email notification template CodeName for your need.)

You can have different langauage versions of email template for your need.

But you should try using the Kentico suggestion at Configuring e-commerce email notifications

Use customer's culture for emails: Specify if the system sends the customer emails in the shopping cart culture.