I suspect it may be used to enforce custom fonts in an old-fashioned way, but nowadays you would simply deliver the font with you site, or use a font service.

Or, it could serve as some kind of "copy-protection", but it would not protect against OCR.

Thinking more about it, this may be a diabolic way to collect strings from people who want to make them "copy-protectable". So you don't need OCR anymore, but fetch them from the source. ;-)

Either way, it's a nice project with a good execution!