Do not get confused like I did.
[item=189500] QUEST OBJECT (Needed for this quest)
[item=187635] CRAFTING ITEM (Drops from mobs)
The Cervid Lattice you need is a QUEST OBJECT, not the usual CRAFTING ITEM that drops from mobs.
It is located inside the Protoform Repository where you get the quest.
There is a [object=375223] at 70.6 27.3 inside the large chamber that contains the quest object.
/way 70.6 27.3 Repository Vault containing the Cervid Lattice
The 3 [item=189501]'s are also located inside the Protoform Repository as follows:
1] On a small table at 70.0 27.7 on the North West wall in between two honeycomb shaped shelves, tucked away behind the smaller shelf on your left.
2] On top of a honeycomb shelf at 71.3 27.8 on the North East wall just above eye level.
3] In the top cubby of a two layer honeycomb shelf at 70.7 29.0 on the South wall.
/way 70.0 27.7 Tool 1
/way 71.3 27.8 Tool 2
/way 70.7 29.0 Tool 3
To help answer a question by @Zermatt in this post, let me see if this helps:
You start The Final Song quest line after completing research [order-advancement=1931].
Complete The Final Song quest line starting with Finding Tahli and ending with Judgment Call
/run print(C_QuestLog.IsQuestFlaggedCompleted(65420))
That leads to The Lost Component and finally A New Architect
/run print(C_QuestLog.IsQuestFlaggedCompleted(65427))
Also, to reiterate the good observation made by @RimeRime in this post.
You might think this is a great way to get a bunch of Genesis Motes, an extra Lattice, and an Implementation by completing this with
your other characters. It's not so great, because after you complete this quest with one character, any other character you complete
it with will only get 30 motes and some gold. 30 motes is nothing to scoff at because that might represent an hour or so of killing, but
as @RimeRime points out, don't get too excited.