Thank you so much for the quick reply! Unfortunately, our schedule is pretty tight, with the survey launch planned for next week. But no worries; I am sure we will manage somehow. In the worst case, I'll have to use different survey projects for different English versions.
We are outsourcing the translation to a professional company and they told us that local adaptations of the English questionnaire were recommended. As we haven't received the translations yet, I must admit that I don't know what the exact difference would be, however.