Search engine functionality goes in the sharing\communication app.

DHTs in the '90s already had search & tagging & even some rudimentary social networking, built in.

Networks like Tribler’s don’t really need a lot more features, so much as just raw usage; most people torrenting are still using the mainline DHT, which doesn’t have a search layer.

That’s largely on those users. Advanced DHT search with rich social features, already exists for those who decide to use it.