A few more thoughts.
First, Enyby's pbres and yuryfdr's xpbres (both are on GitHub) both support adding TTF fonts as resources, however they both assume when dumping resources that every resource is a graphic. That's a bug, though I guess TTF resources are unusual.
The SDK's "pbres" will convert BMP files into new-style graphic resources, so it seems like it would be possible to construct a few known BMP images and use the SDK's "pbres -t" and then the SDK's "pbres -u" to reverse engineer the new-style graphic resource format.
If you disassemble the SDK's pbres bmp2res() it looks rather complicated
