some say that if you listen carefully, you can still hear the screams of bronies in the wind

So, let me get this straight.

So far, here are the pivotal, historic, game-changing events that have taken place over the course of the series that are worthy of the coveted stained glass windows, so that they may be remembered by all for generations:

1. The defeat of Nightmare Moon/redemption of Princess Luna by the Elements of Harmony

2. The defeat of Discord, an omnipotent reality-bending spirit of chaos, by the Elements of Harmony

3. The rescue of the long-lost Crystal Empire by Spike, enabling the Crystal Heart to defeat King Sombra

And finally…

4. The deification/immaculate ascension of Celestia's pet pupil to Alicorn royalty for finishing someone else's unfinished spell that proved to do nothing useful, besides transport her to some astral void where she was rewarded with a full-scale race change… for finishing the spell. That, or just for having a well-rounded personality/using her friends as stepping stones.