Edit a file in a module?

With your Edit → That seems what you have to do.

But indeed, I would highly recommend making a backup, then one you edit.
Once edited, you can just upload it to the forge again with the changes. You could follow How to upload a modified version of a module/system for the process, as it aligns with worlds too.

If any more questions I can do an in-depth step by step tutorial for you, but I it seems you have control. ^^