Thought I better get to this post topic before I head offline shortly (moving day).
There are a few steps to getting the font icons into the theme as an updated version.
1. When you download the newly updated fonts, open the CSS file and copy everything and then paste it into your child theme stylesheet (make sure this is done above any custom CSS you did).
2. Make sure the path of the font files are like this:
src: url('fonts/icomoon.eot?#iefix') format('embedded-opentype'),
3. The font files as you see in the code above, the eot, svg, etc…make sure the font files are copied and pasted into the child theme in a folder named “fonts”.
I’ve never tried this myself so hopefully it follows the rules of child theme overrides and works for you.