What did early churches do in the Roman Empire when they had monolingual speakers of more than one language? Surely in their cultures they had ethnic strife and language shift and all that. If the early Church still had but one liturgy, then we ought to reflect on the reasons.
The tension is ‘meeting people where they are’ and depicting in living form what the Church expects the earth to become in conformity with the living image of Christ as the head of living humanity, the second Adam. Our Lord met people where they were by going out to serve them and inviting them to appear at his feast; he didn’t simple play this contextualization game, because redeemed humanity is a different culture for everyone born after Adam.
Of course redemption is foreign to us all: we’ve all come from the condition of original sin and cultures of idolatry with their own myths and kings and rites. From those elementary principles, as Paul calls them in Galatians, the Holy Spirit works on our hearts through Scripture, baptism, and the Lord’s Supper and the support of the Church working as one Body.
Ah, but it’s hard: first we need to find out what the idolatries are to which the Church stands as a rival polis to this present evil age before we can know how to touch and redeem them with the gospel of Christ. Only then will we know what one Church is in the multilingual context.