I am just questioning why the categories aren't hierarchical, as the category taxonomy usually is by default.

Did the setting cause any trouble? I would like to activate it in a child-theme, so I can output categories automatically with a shortcode as a list inside a project.

I would like to create a child theme and comment the include of "/assets/plugins/radio-buttons-for-taxonomies/radio-buttons-for-taxonomies.php"
in the functions.php

Seems to work, though ... Anyone tried that before?