Hey! Glad you liked our game.
That was a tricky one to figure out, but inside the Dialogic main scene setup, you just need to alter the touch screen button size to not cover areas you don't want to advance text.
The script and settings will resize the touchbox to be full screen so you might also have to disable that.
I am sorry for the late reply. I just saw your comment. Let me know if you still need more help with this.
And HMU on discord if you need other help/tips for your game. Good luck!