I don't know that the dialogue is any worse than Russian QSP games, but combined with the nonsensical plot, the bad dialogue is certainly more difficult to overlook. For example, I don't actually know why Ria was gone for several days, or if the demon-girl was actually stupidly vague or if it was just the translation. Did we ever actually look for the cult at all?
Regardless, just like the Russian QSP games, I'll keep playing it. I enjoy insanity.