I understand your points, but holy shit, six chapters somehow feels like way too much time, and yet nowhere near enough time. The pacing of this arc is fucking terrible.
Oh, he was shown shedding a single tear in like one panel back in like chapter 123-ish in addition to that other chapter where he sobbed like a bitch about feeling so bad about genociding everyone. Eren totally feels guilty about genociding people except when he doesn't, and then when he randomly does, and then again when he more in-characterly doesn't.
Tl;dr-Isayama had to change his plans with Eren most likely because of executive meddling, and/or fan backlash, and now his characterization is all over the place.
Yeah, the Ymir they're referring to is that god child bitch who let out the pigs and is responsible for all of this. She was seen to still be around in chapter 134, and might be in control of everything...? I don't fucking know. I would've guessed she would've gone through a redemption arc, or some bullshit if Isayama plans on making her suddenly good, but with only six chapters left? Nah, fam.
I don't know what the last half of what the person you were quoting was talking about when they mentioned her providing emotional support for Eren, though.
So, either next episode, or the one after it is when Sasha is supposed to die, right? I can't believe I'm saying this, but c'mon, let her last words be "meat"!