How come the Underwater Dwellers don't have a name. I tried adding them and still nothing.

what is the prefabname and the customname you used ?

"Custom Npc Names, you can add more!": {
"scientist": "Scientist NPC",
"npc_tunneldweller": "Tunnel Dweller",
"npc_tunneldwellerspawned": "Tunnel Dweller 2",
"tunneldwellera": "Tunnel Dweller A",
"tunneldwellerb": "Tunnel Dweller B",
"npc_underwaterdweller": "Underwater Dweller",
"underwaterdwellera": "Underwater Dweller A",
"underwaterdwellerb": "Underwater Dweller B"
}