First off, the Hershey Text extension included with the Eggbot distribution is the same version that was released on our web site.
So far as I remember, the fonts that we adapted did not directly include these extra symbols. The symbols included are displayed with the glyph table, and we did not edit or remove any symbols intentionally. There are *some* distributions of *some* of the fonts that do include international characters, however it appears that they were not in the data that we started with. And some of the symbols, such as the Euro are obviously not in the font data, as that data predates the Euro symbol by quite some time.
We can certainly create new fonts and characters, and there have been other requests to do so. Probably the first step should be to build a modern Hershey font editor– perhaps based in Processing –so that we can begin to add these and other requested font characters.