The Trashcan Sage is adapting the Cyrillicized and incidentally Esperantized variant of the copylefted version of URW Gothic L, which is the URW++ foundry's clone of ITC Avant Garde. The main reason for this adaptation is to change the font's name, so it can be installed side-by-side with other versions of URW Gothic L. Then the Rubujsaĝulo can put the modified font on his website for Rubujo readers to download and install on their systems, to get a truer Rubulo environment, without affecting other programs. (The Sage is compromising on his preference to go for high legibility text fonts, at a few places where a 'logo' font might actually help communicate, because of its artistic relationship to the rest of the appearance.) The Sage was not happy with the font, though, until he used the autohinter in FontForge to redo the hinting. Then he was more pleased.
The FontForge autohinter did better than the original hinting. Go figure.
I have no idea how the hinting is in the commercial version from URW++, which might be improved, particularly in the OpenType version.