I don't know about the breeding but I have had black worms live in the tank for months. I like when this happens as it gives the newts a constant source of food but they have to hunt for (so kind of like enrichment).
Black worms will increase your bio load so be sure to monitor your ammonia and nitrites weekly.
That's how I cultivating my black worms tank in substrate sand with good oxygen and with correct food and enough good bacteria you'll have your self a black worm mini farm. I also add the black worms in axolotl tank in substrate sand the same way, so my axolotl can dig up and eat while the worms can stay alive for month with out causing any problem ( my axolotl eat them up faster than that so I just need to add more worms back in) . Of cause in axolotl tank I alway monitoring water condition so there will be no ammonia spike. With live black worms there're always food available for my axie . Hunting for food is a great exercise. But watching them digging like A beagle looking for a lost bone in the back yard does make me giggle every time I see it.