Hi I noticed that if I force use "Source Code Pro" as standard font for all elements in the image I never have problems with font rendering. In case of "Source Sans Pro" font is just not usable becasue of rendering bugs on mac, windows and linux(?). If "Lucida Sans Pro" is used - no bugs too.
Because bug is reproducable on all platform - it's platform independent bug. Because it's reproducable only with one specific font - maybe it's not an athens issue but bug in font itself and if someone could change/update Source Sans Pro to a newly version or to a similar font the problem will be solved? Cheers, Alex