@Solano
Well, you still haven't explained why they'd spend so much time for Lalo. It took years for Baku to reach Surpassing the leader(both time), I don't think Lalo, who's being chased by Kakerou and has no membership currently, can achieve it within a year.
And it's never mentioned if Nowa knows Jyonglyo's face and background or not.
Plus the organizations Jyonglyo infiltrated before weren't as powerful as Kakerou.
And it's very suspicious that an assassin and a crazy urban legend want to join Kakerou.
Kakerou will figure out the reason behind.
And the most important thing is that if Lalo wins this ban match, Kakerou will allow him to challenge Surpassing the leader by himself.
He won't be able to do that if he uses the way you mentioned since he's being chased by Kakerou. He has to let someone else, who's as smart as him, do that for him.
It's unknown that how will Surpassing the leader be held or whether it's possible to influence it from outside or not, so being able to challenge it by himself is very important.