(@KimJongUndo: I am selecting only the footnote text.)

@macropod:
Thank you. I changed both:
.Text = "\[([0-9]{1,})\]"
to:
.Text = "([0-9]{1,})"
and
.Text = "[" & i & "]"
to
.Text = i
But I still got the Run-time error '13': Type mismatch, with debugging highlighting in yellow: k = .Paragraphs(1).Range.Words(1) - 1

So I ran the advanced find and replace recommended by KimJongUndo and converted all nonsuperscript raised footnote callout numbers to nonraised superscripts (which yielded a lot of changes).

Then reran the macro (still with the 2 above edits), and still got the same error with same line highlighted by debugger.

I'm not an expert in macros. Did I do the edits correctly?