There is actually a way to repeat those one-time events (the glitches I assume). Before doing all these, make sure the app (the VN Game) is closed, otherwise this won't work. Also note that this fix is PC ONLY. I have no idea how for the mobile version.
First, press windows key + R, then type %appdata% then you find RenPy folder, then you should see the Afterclass folder. You will then need to find the file named "persistent" and then delete that. You may close the file explorer after this.
Then, find the main folder of the downloaded game (where the executable game app is located), then head to the game folder > saves folder. Once you're there, you will again need to find the "persistent" file and delete it as well.
After that, you may launch the game again and may now access the One-time event once again! Hope this helps and enjoy 😊