
No hate for this but I'm just sharing my thoughts.
I think the reason why she is shocked at what Cassius and Ein was doing, was because she never thought they would do that, especially Ein. From what I can remember in Chapter one, she figured out that she was reicarnated as Roselia and was conducting everything that was bound to happen. It was never mentioned in the book that Ein has allergies and so on but she did remember that Ein was like his father when he has grown up.
She was even shocked at what Ein had to go through, such as intaking poison, the insane schedule, Ein's lack of rest and so on, and even asked Cassius that she will be incharge of taking care of Ein. Since she reincarnated while Ein was young, she though she could change him.
I think the over all reason for her reaction was she never knew Ein already has a dark side at a young age and that Cassius would also act like that. I think she though that Cassius changed and that they won't go to the wrong path just like in the book.
Again No Hate just sharing my thoughts. If you want to confirm. Try re-reading from Chapter 1. I'm not really sure about all this, but I am only basing this from what I can remember since Chapter 1.

In the next chapter, Ain and Cassius finds out who would try to poison Roselia. Some nobleman (not sure since I can't read raws -.-) was really trying to poison her.
He ordered 2 people to do it. Ain and Cassius found them (more like he ordered someone to find and capture them) and took them to the underground basement (where the keep the poisons and all)
Roselia was really suspicious of what was currently happening so she tried to ask but everyone would avoid answering. She asked this one maid who was trying her best not to tell but her expression says it all. Roselia realized that the tea she and Ain was about to drink had poison. Roselia went to look for Ain cause she was worried (I think cause she started running).
(Back to Ain and Cassius)
Ain and Cassius was torturing the 2 people who attempted to poison Roselia (I think they were trying to get info). The two people was on the verge of death but they did not notice that Roselia was behind them. Roselia called their names (I think) and they both turned around to see her shocked face.

I read the raws but I don't understand it since it was in spanish

They're not raws. It's the Spanish translation.
Raws are the original work, so the Korean version.
SPOILER
Don't reply my comment, please. So the spoiler doesn't show.
Spoiler
Louis went back home and his sister told him about his baby and his wedding.
He then read the newspaper and went back to the palace.
He told the prince about those "rumours" and Maetel explained that the Duke shouted about the baby and that they didn't know who was the dad, so the prince had to prepare the wedding.
At the end, he proposed Louis and confessed that he has loved him since the academy.

Read the raws cause its over 100 Chapter and I think its already complete

Yes it is complete.
I wish I could read Corean....
Raw:
https://newtoki95.com/webtoon/24722?stx=%EA%B5%B0%EC%A3%BC%EC%9D%98+%EC%97%AC%EC%9D%B8&title=%EA%B5%B0%EC%A3%BC%EC%9D%98+%EC%97%AC%EC%9D%B8

The girl that is catfishing will be exposed. Because Asbellus will visit and the ladies were wondering why he was visiting for Ina (FL) and not that catfishing girl (forgot the name) and Asbellus explained and she got exposed infront of people. Anyways serves her right. Karma is a bitch.
Chapter 33 and 34 is when she'll be exposed
Love this but it feels a bit lacking is some aspects, so for some reason atleast some side regarding why Tae-jun/jo's sister hated him so bad and also I kind of wanted them to reconcile with his family, though not sure about the father since he started his trauma, their background family, meeting DongJae's family, etc.