I don't read the same into both sentences. In your version she flips through the book until she casually stops. In the original, she flips though the book and stops suddenly because she spotted something in the book. Sure I might be biased because I know the context of the entire scene, but I view that as a bonus.
I think this will bring it closer to the meaning in the original line. The key difference here is that the stop comes very suddenly and completely unexpected to everybody, including herself. I agree that suddenly should be considered in each case. In this case it fits well because it's a very sudden event like "suddenly a loud bang could be heard and the lights died". The word suddenly tells that something happened without warning and likely quite unexpected.
Other than that I really like the post. I will also add that I had the luxury of reading the VN when it was translated (the start that is. It's not done yet) and then again after Fred edited it. It was an amazing experience. The contents is more or less the same, but the reading experience and enjoyment have been significantly improved. I expected it to be an improvement, but not to the scale that it turned out to be. In fact when I read it yesterday, I realized that despite being aware that editing is a really good thing, I had still underestimated the importance of it. Reading the edited version compared to the unedited version was like... wow. Just wow. I think that's the most accurate description of my immediate impression.