Hi Bastien and Nicolas,
Thanks for the work. I do think the footnote transformation function looks useful, though for now I think I will stick with defining the footnotes at the end of each section and re-sorting the footnotes before refile.  I still think it would be useful to have org-refile move footnotes by default. If I have some time soon I will look at what might be required to do this effectively. I may ask the two of you for help as I am still familiarizing myself with the org mode code.
All best,
Leonard