@Udaya Sadhineni,

So, that property will apply to all KB searches performed on a portal, predominantly on the "kb_search" page. You can actually redirect users to it, info available here.

This page has a "language" widget which will allow users to select which language they would like to see article results in (which is driven by a user preference entry per user),

In terms of the /esc portal, currently via the taxonomy it only performs it's search in the language of the user to ensure their best possible user experience,

If you want to learn more about the topic of localization (especially of the /esc portal) check out my blog post here (along with the webinar recording in it) here,

Many thanks,
Kind regards