I suppose the answer will depend on how the fonts have been restricted. In general fonts are installed for all apps. Maybe the "restricted" fonts are part of the application package? You could try looking inside the package contents and having a rummage around?
Extracted the fonts to my desktop and tried to add them to Font Book but got the following message:
2 Serious errors found. Do not use these fonts.
Corrupt font name.
Font basic parsability x
System Validation x
I've read that the error message can be over ridden but I don't know the possible consequences of over riding the message.
I also wondered if it was a legal kind of thing of using fonts from another app?