I looked at the raws since I was curious about the language the characters were actually speaking.
The use of horizontal as opposed to vertical text to denote dialogue that was English in-universe was a neat detail. I didn't notice that the bubbles were shaped so unusually when I was first reading the translation.
I imagine that must have made the typesetter's job a little easier, not having to deal with the sort of narrow one-column-wide bubbles that can make that job such a pain.