Thank you so much for the kind words and glad you like it~ ^ ^
For fourth-wall breaking, I don't remember exactly how I got and started to use it. I think it's a kind of cultural thing from the platform I came from or I watched too many cartoons and/or anime. You're right that this VN will handle more serious issues. That's indeed something to fix to give you, the reader, a better immersion and impression of not just Reynald but the others as well.
Secondly, this is the first time I write in a visual novel media, because I used to write in the basic novel format, I'm still trying to adjust. The thing I intended to do is to give weight to the writing but still show the stuff rather than tell just like you said. I'm trying to remove that feeling of uneasiness when I see a paragraph or the script is too short (less than 3 or 4 sentences per paragraph).
About Rey and Kos, I was just a bit worried it might be easily misunderstood since it's not like your typical sibling relationship...
All in all, thanks a whole lot for the compliments and critiques! These are things that I will certainly look further into and improve them better!