The Spanish acontecimiento (“something that happened; event”) comes from the Latin contigere (“to touch”).
How did that transformation happen? An event is something that you touch, at least metaphorically, or that touches you. Something that happens that doesn’t touch you is just in your mind: not a real event!
From the same Latin root, we also get a few nifty English words including:
We can see the c‑n-t root in both the Spanish and English words.