That's a really clever way of handling fonts. I'll have to take a closer look at their code, as I guess they need to have some list of directories they search for fonts. That part would be beneficial, as right now one has to configure a custom font with a full path in order for Adonthell to pick it up. Having a platform-specific list of system font directories to search would make that a bit easier.
As for alternative fonts that might be required for certain translations, I'll take care of that when the need arises. Might as well end up doing it the Wesnoth way, though I'd always would want to include the required fonts in the source tarballs and binaries. A distro like Debian might have a copy, but OSX and Windows likely not.
Kai