The Catholic Church is an international, polyglot organisation. It is therefore important for us to use a universal language for certain important texts that must be produced in a definitive, objective, normative version from which accurate translations can be made independently. All polyglot organisations and societies, such as the UN, Nato, the EU, Switzerland, Canada, and New Zealand, have to address the problem that there is rarely an exact way of translating complex ideas from one language to another, which can of course lead to ambiguity and disagreement. Indeed, speakers of international languages such as English, French, Spanish, and Portuguese often cannot agree among themselves the precise meaning of their native language.
This was recently demonstrated by the controversy surrounding a new English translation of the Mass. But what that controversy also demonstrated was the ongoing usefulness of preserving an authoritative Latin text from which to make the most faithful possible translation into the vernacular, and also the value in reviewing from time to time that translation in case of error or change of meaning. Take the particularly difficult clause ‘consubstantialem Patri’. In English this is now rendered ‘consubstantial with the Father’ (Catholic Church current version) or ‘Being of one substance with the Father’ (Church of England Book of Common Prayer 1662 version), although a number of other translations are also used. In French it is ‘de même nature que le Père’, which to my mind means, ‘of the same nature as the Father’, and in German it is ‘eines Wesens mit dem Vater’, which is closer to the alternative English translation, ‘of one Being with the Father’ (obsolete Catholic version and also currently used by Anglicans, who have at least two equally authoritative translations in current use). Interestingly, despite the very close relationship between Polish and Czech, the Polish ‘współistotnego Ojcu’ is more like ‘consubstantial …’ (współ is simply the prefix co-), whereas the Czech ‘jedné podstaty s Otcem’ is more like ‘of one …’ It is therefore important that we have the Latin ‘consubstantialem Patri’ so that we all know what we are trying to say.
But this takes us a long way from individual prayer. Unless we are aiming to become expert theologians, canon lawyers, or linguists, it is perfectly good to pray in the language in which we are most comfortable.
I don’t see a problem praying in your language at home.
Only at home? Most people these days also use the vernacular in church.