Don't want to step on toes or anything, but my workaround was to add the following to the OnEntityDeath hook under the scientists, in case they decide to split out the dwellers like they've done with scientists, it would be caught with a similar mechanic.
if ((entname.Contains("underwaterdweller")) && (!entname.Contains("corpse"))) //npc_underwaterdweller
{
entname = "underwaterdweller";
}
if ((entname.Contains("tunneldweller")) && (!entname.Contains("corpse"))) //npc_tunnelwaterdweller
{
entname = "tunneldweller";
}
Presume alternatively chaging the GetAllKillables would also do the trick.
AllObjectives[QuestType.Kill] = new List<string>
{
"bear",
"boar",
"bradleyapc",
"chicken",
"horse",
"stag",
"wolf",
"autoturret_deployed",
"patrolhelicopter",
"player",
"scientist",
"murderer",
"npc_tunneldweller", //changed from tunneldweller
"npc_underwaterdweller", //changed from underwaterdweller
"scarecrow",
"simpleshark"
};