Oh :( This went from minor to blocking bug. I messed up with the project settings and didn't activate the stretch. I guess you have an high resolution and the sprites are not adapting well. Reducing the resolution of your screen to 1920x1080 would probably be enough to fix it but I'll ask the mods if I can upload a fix because you probably won't be the only one. There's indeed two places masked by the UI and it's mandatory to pass through them at least once to finish the game.
Thank you for the positive feedbacks on the idea though, I unfortunately didn't have a lot of time to smooth everything. A lot of time went into writing and UI to find the best way to provide information.