As one of the QCs of the chapter, I do admit I decided to leave the translation of Koromo's description of Shizuno as was originally done by the translator. (For reference, the original was
厄介.) This was a case where the nuances of language became an obstacle.
Koromo is already describing to Saki that she originally thought no one else is stronger than Kiyosumi. Clearly she changed her mind after facing Shizuno and the gang. This means Achiga has the potential to be on even footing with Kiyosumi. Saki, of course, is expecting someone strong. How do you describe something that is even stronger than strong? "Troublesome" may sound threatening, but does it sound threatening enough that one can consider the possibility of Achiga defeating Kiyosumi?
We have only seen one hand from Shizuno, and the one thing we can derive from it is Shizuno's amazing recovery speed. She is not someone that can be fazed by Saki's
rinshan kaihou. Most players will just attempt to dodge Saki and try to win another way (even Yumi can't pull a
chankan every hand). Shizuno is the type of character who would attempt to challenge Saki one-on-one.
Saki 105 is at the final stages of QC and editing and should be out soon.