@Hedaya,
I'm not a Nook owner so I can't be more specific but it's probably just a case of getting the blue bit right.
Code:
src: url(res:///Data/font/tradbdo.ttf)
On a Sony the directory where the .ttf files are stored is
res:///Data/font/, but to a Windows user it looks like
[Drive:]\font in Sony internal memory.
I have skimmed the thread you referenced. It is not clear what the Nook equivalent is, as one user places the ttf files on an SD card and another refers to
res:///system/fonts as a system embedded font, presumably meaning a Nook standard directory for storing system font files. There is also a reference to
res:///system/media/sdcard
When you connect your Nook do you see a directory in internal memory called
[Drive:]\system\fonts or
[Drive:]\fonts? Only another Nook owner can give you the definitive advice on the above.
Another potential problem is that the epub you are testing has something in its internal css which is stopping your customized fonts from displaying correctly. I'm attaching a very simple test epub which will definitely work with your custom fonts if you get the above sorted out. I use it whenever I'm trying out a new font.