Can't search for subtitles other than english LG TV

Known limitation of the new app preview. You can change to the non-preview version to restore the capability. You can subscribe to the announcement thread to be notified when new versions are available. To subscribe, scroll to the bottom of the thread and change Normal to Watching.

Info on opting out of the preview:

App Announcements:

I don’t have a Samsung, but possibly the same things as with the LGs.