Is it possible to show internal group names on Special:ListGroupRights? This could be done by adding a new column to the table. Alternatively, appending a parenthesized internal group name to the left column would work too.
The rationale of this request is that AbuseFilter's user_groups variable is an array of internal group names. But these internal group names are really hard to discover (I personally would need to either take a look at a site configuration or extract it from a query string like Special:ListUsers&group=accountcreator). Consequently, several AbuseFilter editors in various Wikimedia projects don't know what are the possible values of the internal group name and incorrectly guess that it could be Confirmed users, admin, etc. AbuseFilter's inadequate documentation definitely shares responsibility, but the first step to fix this problem is to provide a list of internal group names somewhere. Special:ListGroupRights seems to be the best place.