Thank you so much for your very useful answer. I had missed the "view" option in Language editor/Text elements which is really an easy way to solve my problem. I am sorry for the delay in answering, I was busy making all the adjustements in the 5 languages but I could recently send it for pretest, and I am now very happy about that.
However, there are other issues such as the number of "undelivered" messages I can see from my mail box (but they do not appear undelivered in the statistics view of the survey). I will make a new post about this. Thank you again.