I've modified the game but only for that in the bottom right corner, so I don't have to put it to a separate notepad file or similar. The rules say no scripting, but also with no exploiting next to it, so I'm not sure. Am I okay with this PB display (as long as the rest of the game is unmodified), or do I have to remove it?

I think this modification wouldn't be allowed as others could exploit accepting modifications like this with malicious intent. You're free to use it outside of submissions though.