@Neurotic Many of the items have special significance to Lumrolur...
Undercommon Map: The map leads to duergar "guidon" south of Easthaven and “cousin’s burial spot” southeast of Easthaven, with notes marking: "...plan to return with an ice-cutter to retrieve the “Black Axe” that my cousin stole and then the coup can be enacted."
Reminder: Your guide in the Dwarven Valley was named Brydum Black Axe. Alma & Zeth also read Undercommon, so if you have enough to respond to in your post, I can have one of them relay this info to party.
Chardalyn Bolts: The 2 black stone tipped crossbow bolts are chardalyn. It calls to Lumrolur. This magical ammunition has the following property: "When you fire this magic bolt made of chardalyn, you score a critical hit on a natural 19 or 20. On a critical hit, deal an extra die of cold damage equal to the crossbow’s damage. The bolt loses its magic when it successfully hits."
Chrysoberyl Gem: The sigil in unmistakable – it belongs to the Muzgardt duergar clan who waged war against Lumrolur's people in the past. The collapse of the mines during that conflict is what lead to a detente between the svirfneblin and the Muzgardt duergar.