For each language translation you provide for your survey respondents you'll need to translate the standard messaging and survey controls, such as, the Next and Back buttons, required and validation errors.
This can be pretty time consuming, that's why if you've already translated standard messaging in a survey, we've built the ability to reuse these standard messages.
Take advantage this tool when adding a new language to your survey. Go to Tools > Text & Translations and click Add Language. Choose your language and select Yes for the option to Copy standard messaging for this language from an existing project. A search box will appear where you can type in the name or ID of the survey with the translated elements and click Add Language. Et voila! All your standard message translations will copy over, saving you tedious data entry time!