Huh, thinking about it, the Chamberlain of the Seal probably considers Mathilde his greatest asset for improving the external relations of the empire
I mean, the dwarfs are obvious. She's more respected than anyone since Sigmar, and has done more for Empire/Dwarf relations than anyone in centuries. Athel Loren apperantly favors her too. Besides having that magic project thing, they apperantly really wanted to talk to her after their adoptions of Ulric. So that's curious, and depending on what he knows, could be taken as them approaching Middenland because of her. That she managed to get a House in their big city... well, it's quite interesting.
But with this? He'll be looking at Kiselv. Prior, the expedition would've been seen as a way to gain dwarf favor. And to be fair, it did, what with the return of a whole bloody Karak full of em. The declared her a dwarf, and all. But you know, that benefits Kislev as well. I means one of their borders is now quite a bit more secure, and they'd know that (sadly, it's too indirect to trigger the coin, but that doesn't mean she can't gain appreciation the normal way). He probably doesn't know about the chalice, though he might've heard that she's seen quite favorably. But this battle is going to catch his attention.
Mathilde basically turned a brewing hidden danger into the absolutely most clean victory you could expect. And she was involved in every step. Raising the alarm. Gathering the troops. Preparing the battlefield (via scouting). And fighting in the battle. The Kiselvites will respect the hell out of it, and they'll appreciate the Imperiyani actually helping for once, and even unasked for! Mathilde will get her share of the rewards, but as a Lord Magister, she's always also a representative of her college, and the Empire as a whole (especially being from the Grey Order), and that means her action here will reflect on the empire as well.