For most Wikipedia projects, you can embed the file normally (without a lang parameter). The Wikipedia will use its language if the SVG file supports that language. For example, the German Wikipedia will use German if the SVG file has German. To embed this file in a particular language use the lang parameter with the appropriate language code, e.g. [[File:Diagram of a two-photon excitation microscope en.svg|lang=en]] for the English version. Do not specify a lang parameter if it is not needed. The parameter may prevent the use of a subsequent translation.

To translate the text into your language, you can use the SVG Translate tool. Alternatively, you can download the file to your computer, add your translations using whatever software you're familiar with, and re-upload it with the same name. You will find help in Graphics Lab if you're not sure how to do this.