It would be useful if Firefox recorded which configs the user changed. Imagine if you could view a chronological, tabular list of all configs that you changed. Name, default value, changed value, date.
I mean Tools menu -> Page Info -> Permissions
An example: the gong doesn't sounds when a game starts in lichess if you have autoplay disabled for sound. You need to allow that for the site. There are other configurations there like accepting cookies, etc.