The function org-footnote--allow-reference-p seems to be restrictive.
Does it need to be so restrictive?

1) Why not allow a footnote at the beginning of a line?
     (unless (bolp) ...

It would be a footnote definition, not a footnote reference

2) Why not allow a footnote at the end of a headline?
     ((memq type org-element-all-elements) nil)

It was a bug, fixed in 7584200bb88b7995b87f065320886b0813de22dd. Thank
you.