Subirachs has had this matter brought to her attention by Security and has already reviewed transcripts.
Her judgment is that Sevar was not going into subspace, she was correctly estimating that this was excellent good news on the surface of things.
What lies underneath the surface of things remains questionable and it is unfortunately among Sevar's primary jobs as leader of Project Lawful to do that, so she cannot just relax and take her superiors' word about how well things are going. Subirachs can confirm that Keltham's overt behavior looked like excellent news to her. Subirachs cannot, and the Most High and the Queen probably cannot, speak to whether all of this is some incredible plot by Cayden Cailean of which Asmodeus is unaware. If that's so, it would in fact fall to Sevar to not just watch for that possibility but think about it. She cannot take on the duty of a simple slave, here, alas.
But if Sevar is wondering whether she was just imagining things, no, she wasn't, that looked like progress to Subirachs too. Producing that kind of progress is not all of Sevar's given duty, but it is a large part of it. Especially when it comes to the sort of duty that anyone has any idea how to do. And by "anyone" Subirachs means the Chosen of Asmodeus, because nobody else seems to be able to make any progress on it except Pilar and Yaisa as prompted by Snack Service.