The Celtic languages of northwestern Europe exist in a radically different societal context from established official languages such as English and French. Translation into these dominated languages more often than not fails to understand the radically different societal context in which those languages exist. The 'standard' / 'slang' dichotomy, so pervasive in the context of English and French, does not describe the dialectal reality of written expression in languages such as Breton, Welsh, Irish, and Scottish Gaelic. Despite the title, the 'particularities' mentioned in this article are not particular to the Celtic languages but characterise many other dominated languages worldwide. The exemplifications are from Celtic only because we are so familiar with these languages.