Hi! I just went through the first three chapters (14 pages) of your comic. As a reader, I'd like to share my opinions so far.
The art has a spooky vibe to it so it drew me in. It has great potential. The problem would be the content building. As I only understand English, I couldn't understand the other language that you wrote, so if it was the brother cursing his sister or vice versa, I couldn't get the humour behind it! It would be helpful if you can stick to only one language.
In case you are introducing a concept unfamiliar to a new reader, it would be helpful if you mention what it means with an asterisk under the panel. For instance, when you used <> and << >> in conversation, if you had added the meaning of those with a " *<> means conversation is in English" under the same comic panel, I would have understood immediately. It just makes the read more comfortable.
I'm confused about what kind of school she is in. How did she end up there? What is her situation exactly? Did her parents give her away? Did her and her brother commit some trouble to end up there? I'm guessing you would reveal the information as the chapters progress but confusion is a very strong reason for a reader to shy away from your work! If you could introduce the character's thoughts on this school, something like "This is where I've been stuck in. A nightmare," and then add information about her environment through her thoughts (e.g. "These pills are for your good, they say. Ha!"; "The teachers here don't teach, they dictate"; or "Another word for dread? Prefects.") it would have been better.
On that context, I liked the pacing of those lines that you used at the beginning when she was about to eat the pill, the ones about a healthy body and a healthy mind. It builds up suspense as well as gives adequate information to help the readers understand what's actually going on.