When Basil's vision returned to normal, just a few seconds had passed. In Iliana's eyes, he had merely been staring at the photographs in the journal blankly for the past few seconds, so she didn't think much of it.
In her mind, Basil was just shaken at seeing what his father had experienced. She was also a little bit shaken at the magnitude of the atrocity the Supreme Court had done to Halton under the Church's instruction—it was normal for him to think that way.
It would have been better if they had immediately executed Halton, but they had tortured him by giving him many semi-fatal injuries. Iliana didn't need to experience it—she could imagine what kind of pain Halton must have been enduring before being executed.
"Are you all right?" Iliana looked at Basil.
"I am all right."
"You currently look like someone who will reduce a Kingdom to ashes however."
As you have already realized, it is revealed that [Visualization] doesn't only let Basil see what is away from him as if he is there, but also allow him to visualize a certain event as long as he has enough catalysts or, as the Guide likes to say, "pieces of history" that are related to said event.