It's hard to say. Could be that the neighbor's cousin is a big fan of English manga or perhaps works in the industry related to it. But it's all just speculation without more context.
In many mangas, the relationship between a neighbor and a cousin can be quite complex. Sometimes they are just casual acquaintances, while in other cases, they might have a deeper connection or shared experiences.
I think there's no direct connection. Manga Rock was known for hosting unauthorized manga, while 'A Bride's Story' is a standalone manga with its own publication and distribution.