FlaggedRevs is installed on the hindi wikipedia as can be seen from Special:Version. However, Special:PendingChanges gives a No such Special Page error. Also, the entire section of the FlaggedRevs special pages is missing from Special:SpecialPages. An API query shows that there are still pages in the mainspace with unreviewed pending changes. I was able to review one of those listed in the api query result, but still get a No such Special Page error.
If I understood the flaggedrevs config correctly, it seems that its no longer enabled for the mainspace. It used to be enabled for the mainspace AFAIK. Not sure if this is linked to the problem.