For historical and consistency reasons, all SVGs in optaplanner repository use Airal as the sans-serif font and Courier New as the monospaced font. These fonts are not available on Fedora out of the box and don't seem to be easy to install.

On the other hand, The Liberation Fonts "is font collection which aims to provide document layout compatibility as usage of Times New Roman, Arial, Courier New" and is licensed under the SIL Open Font License.

Switching to Liberation fonts seems to be a wise steps to avoid possible licensing issues and hopefully will make it easier to achieve consistent results when generating PNG images from the SVG sources.