We save the terms and conditions checkbox data in a Shopify meta field. You can translate the Shopify meta field by using a translation app.
metafield: relentless.terms_and_conditions
You may need to contact the app developer you are using to translate the site for assistance.
How to translate the terms and conditions checkbox text with the Translate & Adapt App
You’ll need to change the default text in the app so it shows in the metafields. You can do this by adding a space at the end of the text.