Consider that you are working on a survey/ questionnaire method (cross sectional analysis). Is it necessary that the questionnaire MUST BE translated into the native language?

The original authors/designers of that particular questionnaire - would they accept for a translation?

Apart from copy rights issues, is it ETHICAL to do such thing?

If your subjects can't understand the meaning of some questions, and in a situation where one may have to explain a few words for them, don't you feel that TRANSLATION IS A MUST?

Kindly share your expert opinion.
(I wish you all a great new year ahead..!)