Trolls apparently dont bury the dead, but didn't Vriska find something in a crypt with Equius's sign? Or am I misremembering?

It wasn’t a Tomb, it was Buried Treasure. Either that or literally Darkleer’s Hive buried from some natural phenomena over the years.

Also they do bury their dead. They don’t TYPICALLY bury the dead, but it’s still known enough that I believe Karkat referenced Coffins once. They do not have FUNERALS however, which means they likely just disrespectfully ditch corpses into a hole and leave them be.