The journal begins in Common but switches to Supernal near the end, after the Stormcrows found the Wrathstone. Prior to that, it reads like any other successful adventuring party’s might.
Agera and her two companions, Illugi Swordbreaker and the Emerald Warlock, constituted one part of the Stormcrows. It is clear from the journal that there are other groups that are part of a broader Stormcrow company. The Stormcrows were mercenaries, adventurers for hire. The part of the Stormcrows made up of Agera and her companions worked briefly in the interests of Karrnath and Cyre during the Last War, as well as the Twelve’s Acquisitions Directorate (the Twelve is a centre for arcane research and the potential of dragonmarks, maintained by all of the Dragonmarked Houses). They had two successful expeditions to Xen’drik on exploration and item retrieval jobs for the Directorate. Other clients included the Emerald Claw and the Aurum.
It is clear that money and similar rewards were what motivated the Stormcrows.
Late in the journal, Agera acquires an amulet set with a kyber dragonshard that she names or determines is called the Wrathstone. After acquiring the Wrathstone, Agera becomes more and more paranoid, recording increasing hostility towards her companions, believing thay sought to kill her and take all that was hers—especially the Wrathstone. She finally indicates she’s had enough: the last entry, dated about five years ago, states only, “Tiamat, you have shown me the truth!”