I'm really glad you noticed this project, it was the first one I did and I'm glad to know that there are people still playing it today. It is possible that, as it appears on the main page of the game on itch, you experience this error because of this: "...you can experience some problems in "macOS Sierra" and "Linux Mint 19.2" operating systems."
Be that as it may I am sorry that you are experiencing the this error and I hope you find some way to fix it. On my side, being a development created with VisualNovelMaker, I can't do anything to fix it; I'm sorry.