on a couple pages, we have statements such as "the league was played in a round-robin format". Is there additional information in that statement or is it repetitious? Are there any leagues that are not round-robin tournaments?
I don't see why league is listed as a distinct tournament format. A league is basically a round robin, but it is perhaps more commonly used to refer to team round robin competitions.
There are leagues that are not round robin (eg: the last league of the Go Bundesliga, which is 9 rounds Swiss with 22 teams).
I think the page is misnamed. "League" is not a tournament format. Round robin is a tournament format. League is simply a term for "group", which seems to be mostly used when there is a promotion/demotion aspect involved (as is the case in the Honinbo League, or the Go Bundesliga).
I think this page should be merged with round robin and then deleted (with references updated to say something like "is played in a [round robin] league format", or similar phrasing.