Why did Taravangian request Jasnah's help?

[Kaladin Zahel]

The title refers to when Jasnah soulcasts the fallen stone blocking the room to Taravangian's granddaughter. 

Im reading WoK for the third time and just noticed that Taravangian has a member with a Soulcaster, the man who acquires Szeth's Oathstone.

So was this a Diagram plan to verify Jasnah's true Soulcasting capability? If so, then why qive her assistance by giving her access to the library and not dealing with her immediately after?

Was it a writing error which seems to be a rare Brandon occurrence?

Or is there something I or we are just missing?

Thanks in advance for any assistance.

[Spoolofwhool]

It would be very suspicious if it was revealed that Taravangian had a non-ardent soulcaster working for him. It's also possible and likely that the guy simply wasn't there at the time. The guy seemed like a field agent so he's probably out of Kharabanth a lot.

[Yata]

I think the scene happen for a double reason. In part could be for the reason you already exposed.

But Mr. T can't simply openly use a secret soulcaster....the people Will Talk about this "miracle"....Lastly if Mr. T was in One of his kindly days, maybe He was to worried about the girl to wait.

We know the Diagram has strictly rules about T's Power in the organization depending on the day. Maybe he knowed they never let him use a secret resource that day

[Modal Seoul]

I think Taravangian was assessing whether or not Jasnah was actually a Radiant.

[Oversleep]

DISCLAIMER: I assume the fallen stone was a random thing and not orchestrated by anybody.

Well, maybe the Soulcaster was away at the moment. Maybe Mr.T wanted to check whether Jasnah has a Soulcaster or is a Radiant; then he could have given her access to library to keep her in Kharbranth to keep an eye on her.

It's worth pointing out that Taravangian did not order to kill Radiants as Kaladin was used in Graves plot and not assassinated when he was injured and weak.

Given the fact that Ghostbloods were at odds with Jasnah maybe Mr.T wanted to bait them; on the other hand, Mraize knows about Taravangian and dismisses him as not important so either Taravangian was really subtle about it or did nothing like that.

[Weltall]

I doubt he was trying to test whether Jasnah was a Radiant because to confirm that you'd need to see her Soulcast without the fabrial or do something outside the normal parameters of the thing. So far as we can tell, there's nothing in that scene that doesn't fit how fabrial Soulcasting is 'supposed' to work. Jasnah uses the thing to disguise her talent so she's presumably avoiding any suspicious uses outside of extreme circumstances. Granted, we don't know enough about the mechanics of fabrial soulcasting to be certain (Oathbringer is supposed to have an interlude from an ardent soulcaster so we'll see what we learn there) but it doesn't seem likely he was testing her. The Diagram has other points it tells its followers to look for in determining proto-Radiants.

And yeah, Taravangian's own Soulcaster might not have been on-hand.and even if he was it couldn't be used without potentially arousing suspicion because Kharbranth isn't supposed to have any of the things. He was also in one of his less-intelligent days, meaning he was more compassionate. It's entirely possible that he simply used a resource he had on hand without an ulterior motive, though keeping Jasnah in the city and getting a sense for what she was researching could certainly have been a nice side benefit.