If an account has multiple Language Processing Rules, but the same list of Variables (non-translatable words) across the board, you have to manually upload the variable list to each Language Processing Rule whenever there's an update - for example, whenever a new product or feature name is added to the list.
It would be much more efficient to have a DNT (do-not-translate) list be a resource that you can add to the Language Processing Rules (or to a Project Template, or a Translation Engine), so that you only have to update the list once.