So, I checked if the Maximum Traffic Today resource on interfaces still used UTC time to define today, as in we are at UTC-5, so it considers today to start at 5 AM, and I see it is still broken.
And there is still no reply to this message.
Maybe instead you just make the resource calculate Maximum Traffic Last 24 Hours, instead of Today?
Of course, since this was apparently discussed in 2009, I suppose I shouldn't hold my breath.
I'm not sure what your question is. In your original post, I wouldn't say the data was incorrect. It would all depend on your office hours which you haven't specified.
And even if you set your traffic for the last 24hrs, the time stamp is still going to be out unless you set it for your correct time zone.