Thank you, I hear your advice loud & clear !!!
The same red flag that you and Adoby have put up in front of my eyes have convinced me. In fact, the files I would have really messed up big time are my Cherrytree (note-taking) files, which I edit every day, several times/day. I did 1 small test with a shared file (Windows-Linux) by changing a phrase a bit in Linux & see the effect in Windows. The result was perfect, so that would have encouraged me to do a bigger scale editing exercise.
I just told Adoby how I will handle Calibre, and will exercise extreme caution with all my files. If I want to test a Windows-based file in Linux I'll just clone it for testing purposes.
Best regards.
P.S. I like your avatar !!