Those of us who missed one of the Cup events have to wait longer than a year–significantly longer, it would seem–to be able to access that event again, and there’s no guarantee we will be available in the next window.
My suggestion is that, upon completing all achievements for a currently-active Cup event, all previous Cup events (and associated rewards) should become available to that character; e.g., since I have earned the “Northrend Racing Completionist: Gold” achievement, I should be able to access the Eastern Kingdoms Cup event that I missed last year. The Eastern Kingdoms Cup was Oct. 4-17 2023, and, according to the in-game calendar, it will not be available again until April 23, 2025. This is absurd.
Alternatively, in the final month or two of Dragonflight before The War Within launches, all Cup events could be active for a “last hurrah” to give us a chance at completing Cups we missed.