This is possible, using Signing Brands.  One of the aspects you can set up with Singing Brands is the language that email messaging is displayed in. And because each template can be assigned a different signing brand in its Advanced Options area, you can effectively have 1 signing brand that is set to Swedish, which you specify as being the brand your Swedish Template uses, and one signing brand for English, to which you assign to your English Template. 

Here’s an article in our Support site on how to set a language within a signing brand

And here’s an article that showcases all of the Advanced Options available for templates, in which you’ll see where you can choose a particular signing brand for your template.

Thank you for your question.  I hope that helped!

I think this will solve it! thank you!

However I dont have a “Add brand” function under Settings->Brands. Is it due to the plan or what?

You’re likely correct.  There is a back end feature that allows for Multiple Signing Brands that may be enabled or disabled by an employee of Docusign.  If you would like to get that enabled and confirm its status, I would recommend creating a ticket with the Support team by logging into support.docusign.com or talking to your Account Team.

Good luck!