I do all you write, and so, i have understood my problem and the mistake.
I use multiple tools for my users, and opening script in editor. When opening in, the UTF8 seem to disappear (Automatic conversion ?), and at the next import the data are corrupted. Now i activate an option for UTF8 in the editor, so copy/paste works fine.
In the past i have not this problem, and dont know why. Could you add in the comment of the export, something to tell that script is in UTF8.
Thanks a lot for all.