Mandragora tte Baretara Toubatsu desu ka?: Hana no Majo no Hohoemi wa Kanchigai no Tane o Maku - Ch. 7.2

[Kireato]

Again, the chapter showed the flow of events.
https://mangadex.org/chapter/e714d0eb-d926-4a6f-b1a2-feae7c94914d/18
He responded to her voice first (telling the stranger to go away, because, y'know, his own curse)

https://mangadex.org/chapter/e714d0eb-d926-4a6f-b1a2-feae7c94914d/20
She literally thought he might've collapsed because of her curse, then check but there's no mark.
Given she's a reincarnator and doesn't really know how her voice truly work, maybe she just assume he was far away enough to not be cursed but still was affected by it.

https://mangadex.org/chapter/e714d0eb-d926-4a6f-b1a2-feae7c94914d/29
On his POV, he felt an approaching presence.
https://mangadex.org/chapter/e714d0eb-d926-4a6f-b1a2-feae7c94914d/32
Woke up for a moment and saw her and nobody else.

And here's the one key point you seem to keep forgetting: HE RECOGNIZED SHE IS NOT AFFECTED BY HIS CURSE.
To his knowledge, for someone to not be affected by curse would means they're also cursed.
So if she is cursed as he expect (and 'confirmed' in this chapter) then it'd make sense for her to hide her voice and pretend to be mute, the same way he hid his cursed eye.

Yes, I was definitely forgetting he recognised she was not affected by his curse, and that led him to his conclusion in this chapter.

The problem I have is with https://mangadex.org/chapter/1ecf91e6-133d-4d2d-9ba0-f956afb1ca7c/19 where she instantly assumes he knows she can speak.

That's strange because, as far as she knows, those who hear her speak, die. Note that, as you said, she thought he was collapsed because he heard her voice, but she checked for the curse mark, realised he didn't have it, and then saw that he was heavily wounded and needed treatment (so your comment about being far away to still be affected but not be cursed is plain wrong; she knew it wasn't that). Additionally, when she saved him, he showed little reaction, as he was mostly unconscious due to his wounds. As far as she could tell, he was just sleep-talking from delirium instead of actually responding to her. The conclusion she should have reached here, since she doesn't know about him being cursed cancelling her own curse, is that he couldn't have possibly heard her.

In fact, the main reason I recollected the previous events incorrectly is the page I linked; they're shown in visual range of each other and he's telling her to leave him alone.

 

[WhimsiCat]

That's strange because, as far as she knows, those who hear her speak, die.

Literally ch 1:
https://mangadex.org/chapter/7b39e72b-091e-47a3-9c2d-4a971db15636/37

Or here, another one:
https://mangadex.org/chapter/b57a7d3c-2d43-4c1e-9402-f56f1bea0bfc/27

So no, you're absolutely wrong on that.

mostly unconscious due to his wounds.

Ah yes, being able to sense something approaching and even remember what she looks like, totally 'mostly unconscious' behavior.

The conclusion she should have reached here, since she doesn't know about him being cursed cancelling her own curse, is that he couldn't have possibly heard her.

No? If any amount of her voice can apply the curse then considering she was SCREAMING earlier the area of damage should've reach very far the early pages of the manga would not make sense.

 

[Keansor]

Page 19: Honestly he sure does some leaps of logic (even tho he's right). Notably in WN none of such speculations were present. He decided to side with her mainly because he sympathized with what he thought is a voice curse making others hate her as his eye curse does. Kinda posessive and creepy, but here he just randomly goes "she gotta be the root cause of it all, but Imma do nothing 'cause, uh, she saved me?"

My guess is that it was for time constraints. We haven't been given an establishing moment where he shows he's actually pretty selfish instead of the "ideal knight" he pretends to be (although he has implied it), unlike in the web novel where it gets clearly established in his thoughts during a chapter from his POV.