You should both test and listen to what people want to have.
If they're indeed able to send ambushes to the lizardfolk that just pretty much means they can't be immortal without making playing as them unduly difficult. Is that how it goes if they have trade tags only?
They're definitely at war with lizardfolk in my newest world, just checked.
In other news, I've now grown to occasionally hate my creation. Trolls sure like to hang out in dungeons. You can expect to find them there, living under the city, among piles upon piles of rings, earrings, figurines and crowns made of various creature materials such as mallard keratin where I'm sure they're happy. Never in big groups, always in narrow corridors... or maybe I just don't make it that far. I must have lost five adventurers now this way: open door, stepping in. You have been spotted!! The troll smacks you around with his troll meteoric iron hammer. You have fallen unconscious. You died. Time to restart, again. (Well, to be fair, this used to happen with goblins too in vanilla. And they're not impossible to win one on one in melee even as a starting out halfling hero if you have a good weapon, but it's pretty damn hard if they get a first shot in.)
Sending in a troop of halflings with superior numbers is very valid strategy. Even a few useless hunters can overwhelm a troll when they just wrestle it like angry lemmings while you're free to deliver a killing blow. Luring them out of the dungeon for halfling peasants to rip them apart works too. And since halflings can wield one two-handed, appropriating a troll hammer and swinging it around is then so much more fun.