Along with reviewing and making corrections to the numerals in Cantarell Regular, I also looked over a small set of symbols used for mathematics. Some of them—such as the # and *—were heavier than the rest of the design and stood out as bolder. Others—like the %, ‰, ° and ^—were too light.
See related bug 703260.
And while I didn’t find the time to tackle this during the internship, I have raised a new bug with a short list of missing mathematical symbols as well.