If you want to find troops that do event damage, search for the traits: Godslayer (Raid Boss), Siegebreaker (Invasion), “Bountyhunter” (Bounty). You can also search for “Boss”, though that might be a little noisy.
Trait filtering would be tough. There are currently 599 traits. Imagine trying to use a drop-down list with 599 items! Besides, the name of the trait doesn’t always tell you what it does. “Wood Ancestry” isn’t very descriptive, is it? There’s not really enough room in the UI to display a drop-down with the full ability text.
For right now our best bet is Gowdb. I’m working on a tool to make a fuzzier kind of search, but progress is slow and “search UI” is the part I’m bad at.
If you could figure out a way to present the 599 traits that’d make it easier to figure out which one you want, I’m totally open. But like you said, the name alone isn’t the best choice.