I spoke with the mod named "Just Old Now," and they said you're fully allowed to update the itch.io page whenever you want. However, if you want to make changes to the game files, you need to get permission from one of the admins or mods first.
I also asked about what changes are allowed. There was a glitch in the first level related to the portal and instructions, and he mentioned that if a bug or problem is breaking the game experience—like in my case, where players don't have instructions on where to go and what to do—you can make those changes. Small tweaks to your existing code are also allowed, as long as you’re not creating something entirely new.
For your case, since you only want to change a couple of lines of code, you might get permission for that. Just ask in the help section of their Discord server: Discord Help Section.
Best of luck with your stream game also!