Default labels in Quiz Preferences, when changed, do not transfer to the master slides. I don't remember since which version that bug appeared. I have logged it but localisation is very low on the priority list as I have experienced since over a decade. This means they will not be applied to existing quiz slides, but only on new quiz slides. You may have checked the Object styles for the Quizzing category, you'll see that the default labels have changed there as well. I have tried a lot of workflows: trying to make a new object style default for each of the quiz buttons, saving the theme and re-applying it but nothing works. Personally, since I need to localise courses, I am using this workflow, but it may not be what you expected:
- I always put the question/answer texts in a GIFT file, never do it right away in the course. Importing such a file is a breeze. Eventually it may be necessary to edit the layout of the quizzing master slides (which can be saved as a custom theme).
- To localise translate the GIFT file.
- Import (or edit) the proper Preferences. I have preferences ready for each language. That will take care of the labels.
- Delete all the existing questions.
- Import the translated GIFT file. Since text in another language can have a different length, checking out the result will be necessary.
Why do I not use a CSV file? Because I really had issues with a translated version, as I explain in this blog post:
http://blog.lilybiri.com/tips-to-localize-a-quiz