I accidentally ran into a thesis work which featured Magi in it. I tried to look for others, but found none. If you know others, you can contact me. Still, I thought it was a fun discovery, so I have translated the Magi part below.

Name: Mangan luonteesta – Tunteen ilmaisusta japanilaisessa sarjakuvassa (Of the nature of manga – Expression of emotion in Japanese comics)
Author: Inga Metsola
A polytechnic level thesis from Oulu University of Applied Sciences.
A link to the thesis.

On pages 29 and 30, Magi is used as an example when explaining the use of background effects in manga. The examples used are from Hakuryuu and Hakuei's conversation in Kou (after Koutoku's funeral), as well as from Hakuryuu confronting Hakuei's illusion in Belial:
"In the situation, every character is fairly still. In upper right corner, big sister Hakuei grabs onto her little brother Hakuryuu, so there are lines centralized to the event in order to portray the intensity and dramaticness of the action. Next to the panel on the left, the lines turn vertical, and at first, there are less of them from Hakuryuu due to the short distance. This describes the intensivity of the moment, but the inner clarity of mind of the character is also shown. Instead, the vertical lines behind Hakuei are stronger and closer to her, portraying distress. In the middle of the page, shining, though not literally, is Judar, whose powerful and determined presence in the situation is portrayed centralized with dense, contrasting lines, which give him influence. In lower right, Hakuryuu's background is empty, in contrast, because he is fully calm in the situation. Next to Hakuei at the bottom diagonal, dense lines portray a moving object (shown on the following page). In the same comic there is also a panel in which Hakuryuu is shouting at his sister, and out of the lines in the background, an explosion-like element has been built (picture 9). The effect doesn't portray a literal explosion but Hakuryuu's explosive emotions which are targeted towards Hakuei."

The Magi page the author is talking about can be seen on thesis page 56.