Flacon is an audio file encoder that extracts individual tracks from one big audio file and separates them into different tracks. It can also convert them in the process.
Flacon is available for many Linux distributions and can be installed on KDE neon with an easy.
sudo add-apt-repository ppa:flacon
sudo apt-get update
sudo apt-get install flacon
Simply select the destination directory, the pattern you want your files to be renamed as, what format you want them converted to and whether you want to apply replaygain. Then convert. It takes a surprisingly small amount of time.