3)Akira will be in the center of this change since his infidelity kinda got revelealed
It hasn't yet though.
She's bothering to go through Yumi's phone so she's looking for proof. Unless Yumi has a bunch of messages on her phone saying she wants Sensei's dig bick which she never sent to Sensei (and most likely hasn't got a history of messages of them sorting out logistics for this affair), that'd still only incriminate her not Sensei. She hasn't had a chance to take photos of both of them fucking unless we start going supernatural either with Akira blacking out, or her having photos of previous lives that survived resets on their phone.
She's pretty primed to go back to the status quo, maybe with a lower opinion of Yumi which might go somewhere. Maybe they just blow everything up instead (Might as well do the crime if you've done the time)