In Search screen, "Redirected from: $1" is sometimes displayed and sometimes "$1" is in searchSite's language, sometimes in other language, and there does not seem a way to get at MWKSearchRedirectMapping.redirectFromTitle's language. We need to find $1's language in order to be able to set accessibilityLanguage of that part of the label so that VoiceOver reads it properly.
E.g. after setting Czech language in search, searching for "Köln" (German for Cologne ) finds Kolín nad Rýnem (Czech for "Cologne upon Rhine"), and adds "Redirected from: Köln am Rhein" (German for "Cologne upon Rhine") which is obviously a German article (though I found only article for Köln). So here, "$1" (i.e. "Köln am Rhein") is in German, which is neither the UI language (English) nor the search language (Czech).
This part of string (i.e. "$1" in "Redirected from: $1") would then have UIAccessibilitySpeechAttributeLanguage set to the proper language code if it differs from the UI language.