HarmonyFlex register to the post-package-install event, who occurs after the package is installed and performs some tasks when predefined package types are loaded by Composer.
Here is the details about the different supported package types when Composer require/install a dependency.
They are identified by the Composer type harmony-theme who install the theme to the next location: themes/{$vendor}/{$name}.
They are identified by the Composer type harmony-translation who install the translation to the next location: translations/{$name}.