Trolls do stop following you, not sure why yours didn't, their leash isn't very long at all.

What you are referring to isn't a bad design at all, quite the opposite. You can't walk into the next biome wearing gear from the previous biome and expect to face tank all the mobs in there.

Therefore, the best way to kill them is upgrade to Bronze buckler (using materials from the black forest) and parry / melee but until then use a bow which is perfectly fine though slow.

Fastest way with a bow is to just stand there, once they swing, step back so they miss you and shoot with arrow and then taunt them to swing again. It's just faster and less stamina consuming than running around the forest shooting arrows. You can also get them to cut trees down for you in this way, useful if you need fine wood and haven't made a bronze axe yet.