I vaguely remember this hymn in the Tāittirīya-saṁhitā́, I'd like if anyone could tell me where.

An eminent Madhwist scholar says it is not authentic. https://sites.google.com/site/madhwaprameyaqa/home/isckon-qa---hsvj Garga Samhita is a spurious work, very likely the creation of either Gaudiyas, or some others. None of our standard commentators mention this work. Lot of theories developed ...

I imagine If a person living in usa or anywhere in the world like Africa or anywhere is peaceful loving and worship God but do not know about anything about moksha will be get moksha or he will again born in Aryavarta to follow teachings of vedanta and than allowed to be free