It's too late to assist the cartographers in completing their mission, but it appears they collected the data Harbinger Mikolaas was expecting. The crystal storing their survey information was not among their ransacked packs, so it must be in the hands of the Wrathscalenaga.
You know that Harbinger Mikolaas will be saddened by the loss of the survey crew, but would want to salvage the survey data.
<You tell Harbinger Mikolaas of the survey team's fate. He accepts the crystal from you, but remains silent for a long moment.>
They were good men, <name>, and they knew their mission would be dangerous. I'm grateful for your help in locating the team and recovering the crystal.
<The harbinger's fists clench.>
We've lost too many good men already, and our mission has only just begun.
The Survey Data Crystal drops from any of the nearby naga. As is often found with this sort of quest, the number of kills you have to make varies widely. Some have reported it to have dropped in only a few kills, some have killed upwards of 30 naga before finding it.