@Shita-kiri Suzume Well, because it's not really a bean soup. It's a dessert made out of sweet beans and rice cake. Additionally, these things are labeled in Cyrillic as Каичу Сирко (Kaichu Shirko).
But, probably, the main reason and the most honest answer is that English translation is to some extent derived from my Russian translation. Cyrillic labels are more obvious there. so I kept the name and made a commentary page. When doing the English translation I just stuck with how it was without a second thought.
On a sidenote, I find it really strange, that Hayami Rasenjin, being such a Slav culture aficionado, made a traditional Japanese dessert Martina's favourite treat.