with a PoW that has 5 00s in front that is only 3 bytes, or 16777216 possible different first 8 bytes then would be better to at least use the last 8 bytes than the first for this reason (PoW)

In the interface I built, it shows both events, so in the event of a collision you get more results; you can probably determine which event you were seeking by context. The likelyhood of more than 2 results is astronomically low. Also, 6 words is a goldilocks default but you can use as many words as you want to ensure you don't get collisions. If you find a collision with your event, you can add 1 more word to probably resolve it. It's very flexible.