All default text populated as part of bundle creation and design is 100% editable and customizable so that you can display your offers in any language.

This also includes the text displayed on the offer claim button.

The only elements needed to be customized in a different language from Settings -> General Settings -> Advanced Settings are the Quantity Label and the Bundle Price. By default the "Quantity" is displayed in bundle offers in English and you can edit the word in Settings with anything else you can even use something more generic such as "QTN" or use a translation.

The Bundle Price Label is only relevant if you are using the Minimalist Tiered Look but it can be changed from the same section in Settings -> General Settings -> Advanced Settings.

Here is a minimalist tiered look offer to see the newly changed labels live in a store: