In general, the delay has been historically accurate (though I haven’t checked today, as no streams have delay that I regularly follow). People like jcarverpoker and a variety of tournaments use delay and are accurately reflected in the api.
Have you tried setting it a few times, and tried setting it through the api as a test? Is it possible your broadcasting software is overwriting the setting with an in app setting for delay (that ends up pushed to the twitch endpoint using an oauth token)?
Could be broken, but I haven’t seen any issues in the past week or so.