You can add these NPC numbers to your
NPCScan addon to speed up the findings, this will give you a warning once the NPC is in the area, so you can go watch a movie instead of spamming a macro 24/7 - Remember to set NPC scan to unmute ingame sound when something is found, and also activate out of game sound in the normal wow options.
Linken - 52233
Nat Pagle - 52244
Mankrik - 52238
Hemet Nesingwary - 52261
Chromie - 52265
Thassarian - 53427
Doublechecked when the quest was available in EU today during the zerg right after reset. And got all with NPC scan, was very easy !
NOTE: If you have some of the NPC's already in your cache you can safely delete the [WOW-Folder]\Cache\WDB\enGB\creaturecache.wdb file, that will reset the cache (While wow is closed ofc)