If all the text is indeed converted to paths, then it isn't really a
character anymore, it's a vector path, so it would be impossible to
actually change it into another character. Have you tried zooming right
into the problem character in Acrobat/Acrobat Reader? Could you upload
the PDF somewhere and post a link to it? This might just be an on-screen
redraw quirk that only occurs at a certain magnification. They will
occur when you convert all type to paths before producing a PDF, so it's
not usually a good idea to do so. Supplying EPS for output might be a
different matter, but I personally prefer to keep the text as text, and
embed all fonts. This will give you better type rendition, especially
on-screen and from low-resolution output devices, due to Font Hinting
and the fact that Acrobat will always anti-alias text on-screen by default.
The fact you are converting to paths suggests to me you are creating
PDFs for output. If so, using FH's built-in PDF export is a no-no, due
to it's pretty severe limitations:
It's much more advisable to use Adobe Acrobat Distiller for such purposes.