justify the interview development, and validation or testing methods Is it common/reasonable for reviewers to ask for including a justification or clarification of interview scrip development, and inquire about piloting, or testing the interviews?
Yes, a reviewer can always ask evidence to justify your sayings to escape from the blames such as if any mistakes found later after the publication. So it is up to the author whether he/she incorporates those evidences/ justifications in the manuscript or as supplements or by giving clarifications to the reviewer.