Internationalize Portal using Translation Sets

I am working on Portal which needs to support multi-language (Internationalization). But to my knowledge, the Translation Sets are based on logged in user's local on sites, and Portal's local is the one defined at the time of publishing.

I can think of a way to use Translation Sets + publishing 2 portals (2 links) to support 2 language using admin console to set the right local at the point of publishing portal. Works well in my use case. But feels hacky and not the right way to implement. 

I saw the attached screenshot on one of the screens in Appian 24.2 webinar screens. Was wondering if there is any well defined pattern of how to use Translation Sets on Portals and if not Translation Sets any other way to implement localization based on user selection on portal?

I am aware that this can be easily implemented using traditional localization methods used on Site + webAPI to portal. But as Translation Sets is build so well and evolving, I want to leverage it hoping the ability for portal user to select/define the local on screen is supported soon.