I am aware that I can pass the redirect string into the shortcode, but that is not always practical. For example in my case (which I think is common), the shortcode is embedded in a sidebar shared in all pages of the website. So overriding the redirect means that users will never be redirected to the right page.
I guess i could write my own shortcode for that somehow… anyway, thanks for the answer and please consider this a feature request to support wordpress with unicode urls 