I must admit that I haven't exactly kept my little GUI up to date

The "latest" version can be found here:
https://github.com/shermp/ReadifyFon...ceImprovements
Goodness knows how well it works. The FontForge folks seem to change/add to the python api as it suits them, and don't exactly keep the documentation up to date (at least it seems that way). They also can't seem to decide whether they want to use Python 2 or 3, which is even more annoying.
Fonttools would be great to use, but as roger64 noted, it is a very advanced tool, however documentation on how to use the thing is.... sparse.
Note with my tool, that it seems to have real trouble with the internal font naming for a lot of fonts, and I don't know why.