All perfect praise be to Allah, the Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
It is not sinful to live in a country without learning the language of its people. However, learning that language is a good and important thing, especially if one is going to live there for a long time or permanently, in order to find it easier to fulfill one's needs and handle life affairs.
Allah knows best.