Myself and a handful of others have attempted to set custom External Variable values through scripting and the config to no luck.

Following the Wiki page here: https://community.bistudio.com/wiki/Arma_Reforger:Audio_Editor:_Audio_Variables

I've attempted this as it's shown, and when I print the value, it's always 0, regardless of what the config value is, or what I set it to through script.