Well, the union events get revived often because it's just these 7. And they don't like to repeat the same event type twice in a row, so union events will show up frequently.
Raid events don't get revived ever (for technical reasons apparently). However, starting in August there will be a way to get the eidolons from them. As for the weapons, they will continue to be permanently missable until ~December, although the currency you'll need for that (orichalcum) is tougher to get.
And advent events as you've seen by now do get reprints. What makes it a bit... trickier, I guess, is that even the DMM schedule's more similar to Nutaku Aigis in that there's typically just the 1 main event* going on a time. So whenever it's time for an advent, it'll either be new or a reprint. Not like DMM Aigis which holds a new event and a revival at the same time, as I understand it.

*main event being advent, raid, or union; ie the stuff that uses up AP/BP. Guild Orders and Tower Quest have their own limited entry system.
Once Guild Orders start in August, they'll just keep running one after another, and there's one for each element. I expect Tower Quest to end up operating in a similar way, but they seem to be having issues to deal with.