The European Union has 24 official languages, and EU legislation is published in all of them. How does the court resolve inconsistencies in interpretation that might arise because of mistranslations, or because of different connotations that a word might have in one language but not another?
See this working paper by Silvia Ferreri for an excellent write-up of this issue.
The key point is that because each linguistic version of legislation is equally authentic, none can be taken as the authentic version. The court then resolves this by applying two principles: comparing the linguistic versions and giving deference to legislative intent. This is necessarily a case-by-case analysis.
The paper calls attention to Case C‑445/09 arising from the Netherlands, where 9 different linguistic versions are compared and shows that the straightforward Dutch reading of the legislation in question isn't compatible with the other linguistic versions or legislative intent. In paragraph 25, the decision also contains a concise summary of the general principle of interpreting laws in multiple languages:
According to settled case-law, the need for uniform application and, accordingly, for uniform interpretation of an EU measure makes it impossible to consider one version of the text in isolation, but requires that it be interpreted on the basis of both the real intention of its author and the aim which the latter seeks to achieve, in the light, in particular, of the versions in all languages (see, inter alia, Case 29/69 Stauder  ECR 419, paragraph 3; Joined Cases C‑261/08 and C‑348/08 Zurita García and Choque Cabrera  ECR I‑10143, paragraph 54; and Case C‑473/08 Eulitz  ECR I‑0000, paragraph 22).