Possibly not necessary to change TTF font names?
I just found on PC if you rename any TTF font to ttf*.ttf and modify kconfig.xml, adding:
<font face="Swis721 BT" href="[bbebFontPath]" engine="FreeType">
<family name="anyname" uses="font family"/>
and change the '<style font="font family"' in connectAssets.xml it would
change the default font Sony CONNECT uses.
If this works on the reader, the great advantage is for PDF files using arbitrary fonts there would be no more 'blocks'. The system would be able to find the correct font family.
I'll try it with my reader later today.