It appears the font rendering issues with Electron based apps have been resolved for Ubuntu 18.04. I could be wrong in assuming this is universally true, but Atom 1.27.1 and greater are now working as mentioned here. In addition, Discord is showing no signs of rendering issues at this time.
If you initially "fixed" the issue by downgrading FreeType's libfreetype6 as explained in my earlier post, you can enter the following command
sudo apt-mark unhold libfreetype6 and run Software Updater to install the latest version of the file. After that you can install Atom from the Ubuntu source, or you can add the official Atom repo and install that way.
Finally, you will no longer need the artful repo from which the downgraded version of libfreetype6 was pulled.
sudo add-apt-repository --remove "deb http://us.archive.ubuntu.com/ubuntu/ artful-updates main" then
sudo apt-get update