I feel that "Sisters Yuri" is a mysterious hurdle for me
Wait, Mochi said that??
The Japanese use "hurdle" as a metaphor for when raising expectations leads to a danger of being perceived to have disappointed. So I believe Mochi is laughing about extra pressure from being best known for sisters yuri, leading to taking this one in a weird direction.
The way Yuri Drill worked, the book was divided into sections for the themes, sisters yuri being one of them, with various mangaka doing a page, so it also means they're kind of up against other mangaka's ideas for what to do with the theme.