Your landlord can and absolutely should evict them. He should be resolving this for you. They have damaged property and are threatening your safety. Him being powerless is bullshit.

Until you find another place, stop engaging with them. Don't knock, don't talk to them, don't text them. You know it doesn't get them to stop what they're doing, so it's no use anyway. The landlord and the cops are your go between. Sometimes neighbors who get along well can resolve things amongst themselves but much of the time you end up with stuff like this. Block them and avoid them.

Good luck. Hopefully these leads pan out for you.