{
        "KillerType": "Player",
        "VictimType": "Scientist",
        "DamageType": "*",
        "Messages": [
          "{killer} did not want to be a part of {victim}'s experiments and killed them using their {weapon} over a distance of {distance}."
        ]
      },

Looking At: assets/rust.ai/agents/npcplayer/humannpc/scientist/scientistnpc_heavy.prefab (UnityEngine.GameObject)
       Ent: scientistnpc_heavy
       Pos: (559.98, 27.53, 1196.80)
     Layer: Player (Server)

I have Better Npc and it works. I just tested it.
Try creating a new json configuration file.

11:00:08 [Death Notes] Luto zastřelil Older Miner svou Assault Rifle na vzdálenost 5.5 meters.
11:00:08 Older Miner[2545188] was killed by Luto[76561198028966303] at (-1390.12, 5.55, 971.11)

Also not working for some other NPCs like some generated by mods like Armord Train or Convoy.

Turret's on some NPC's or all are not coming up in chat when they get killed.

Hi
check the NPC name in the config json.
All these NPCs are scientistnpc_heavy

"KillerType": "Player",
"VictimType": "HeavyScientist",
"DamageType": "*",
etc.

I have all the plugins from ADEM and the message works for them.
ArmoredTrain, Convoy, Shipwreck, Space, Sputnik, etc.

Hello, Ludek and I tested this against Convoy and other plugins and it should be working. Make sure you're using 6.4.3 (or newer), and make sure you start with a fresh (move the old one elsewhere and restart the plugin) config file, and then add back in your death note tweaks into the fresh config file as necessary. As Ludek pointed out, many of these are Heavy Scientists and require those particular death message blocks in order to function correctly.