Ethnio is fully localizable and international-friendly. You can use any language in the world, because every last text field, button, and link is customizable.
If you just have a single international language, the Ethnio screener will accept any Unicode characters. You can turn on "advanced options" on the invite page to change the "Continue" button to your own language. The close button is just an "X" so all words can be totally customized! Below is an example. Other small things like tool tips can be customized from screeners >> questions and the "customize tool tips" box.
Multiple Languages - simply duplicate your screener to create as many languages as you want. For example, if you create a screener in English, and have a French and Spanish version, this will let you easily maintain those different languages.