It's not Scribus, but I think here is this problem best discussed
I wrote my first book 1992 with Calamus on Atari TT.
About 2005, somebody was so nice to convert my old Calamus files from 1992 to
a PDF.
I used SWISS 100, but this font seems to be broken, the conversion to the PDF rendered SWISS100 not like expected.
At starting to write my second book October 2011, I changed from Calamus to Scribus.
I discovered Swiss_721_Black_BT.ttf should be most similar to the old Swiss100
Is it possible to exchange a font in an existing PDF?
Here is the PDF
http://buch.pege.org/aufstieg-zum-solarzeitalter.pdf