Central temple can be found via Utolopis or Enclave statues.
That said...
ALL the 4 first NPC's are also found outside the temple.
The 2 first standing inside the "court yard"
3rd is wandering a bit around them
4th is on the cliffs behind the temple to the east.
It is theoretically possible to combine "Crystal Filled by the Source" with "Complete Blueprint Pattern of 'Infernal Demon'". But you need at least 400 in NanoProgramming. It is theoretically possible to combine "Subdued Flow of Novictum" with "Notum Crystal with Etched 'Infernal Demon'". But you ne...