Nhjela is on the floor below ( 53, 228, -149 ) /waypoint 53, 228, -149, the 3rd floor, and you will have needed to do the first quest she gives you, The Mad Poet, before she will answer your questions about the dragons.
If you want to talk to her during the same zone-run do not click on the mirror on the 4th floor as that will zone you out to The Shimmering Citadel. Instead you need to either evac or die and then run back up.
When hailed and at the end of the dialogue she will give you a book called The Twin Dragons.
Siyamak, like Barakah, will be in his human form in Maj'Dul ( -248, 137, 59 ) /waypoint -248, 137, 59 near the Court of Truth. This version of Siyamak does not update Guild Achievement but does update the quest.
2013-06-03 These steps are either slightly wrong or out of date. It is backwards from what I am currently seeing. Barakh (contested) just popped for me on Permafrost at night 10pm Norrath game time. Also the human forms are backwards from this. Barakh is human in MD during the day and Siyamak is human at night in MD.
2013-11-18 - Siyamak spawned at 11am in The Pillars of Flame at ( 1740, -211, -911 ) /waypoint 1740.34, -210.67, -910.76.
2019-07-14 - Siyamak spawned neither at 3 or 4 am norathian time in The Pillars of Flame at ( 1740, -211, -911 ) /waypoint 1740.34, -210.67, -910.76.