No more news on who the mysterious benefactor helping us is except that they have Tholian access codes in addition to Tal Shiar access codes.
The Tholians are attacking the vault to lure Obisek away from New Romulus, which they have an interest in for archaeological reasons.
They're very interested in Dewan ruins and a Dewan portal device. New Romulus was home of the Dewan, who were slaves of the Iconians and worshipped them. They were attacked by the Iconians' slaves, who banded together and revolted. The Iconians got into their portal and abandoned all of the races loyal to them, which included the Dewan. I'm assuming the Icobar and Dinasians were other servent races of the Iconians who fought on their side in the great war. (The Zibalians may be tied in as well, for the production reason that their alphabet reused Iconian script.)
This planet was bombarded, like Iconia was, by the enemies of the Iconians, and this is the reason Paehhos craeter was formed. New Romulus was a stronghold for the Dewan.
I'm not sure if this all fits in with the novel The Devil's Heart or not. (It was about an artifact created by the makers of the Guardian of Forever that was owned by the Tkon and Iconians, which became known to ancient Klingons, Romulans, and El Aureans.) The heart was a seed that when planted in a suitable place would grow to become a Guardian of Forever. The big point of contradiction would seem to be that New Romulus may be the Dewan homeworld. The heart could heal injuries and plagues and grant dreams. I expect if there is a connection, it could be that the Sword of the Raptor Star (the Romulan artifact hinted at being on New Romulus) was made from it or another Guardian seed.
I really enjoyed this mission and the story is coming together bit by bit.
In many ways I prefer this to the FE as its sort of uncovering the story naturally as you explore around, rather than having it presented in a linear episodic way. Just wish there was more as one map per week is slow progression.