Need Acrobat Pro to display icons that represent a number score - not the number itself.

You’ve come to the right place :) I have not had a lot of luck with AI and Adobe Acrobat JavaScript - this is just likely too specific for AI to get a good handle on how this all works. 

What JR posted should work for you. Just to give you some context: You an add an image to a button (you can have text on a button, or an image, or text and an image combined). For this to work, you will need to create as many buttons as you would like to have score values, and then you stack the buttons over each other and enable only the one button with the correct score. 

If you need to do this in several locations of your document, then create this “stack” once and hide everything, and then only create a simple button with a placeholder image where you want to show the score. 

When the score changes, you can then copy the button image data from the “stack” and assign it to your button face. You can use something like this:

 

this.getField("btnTarget").buttonSetIcon(this.getField("btnSource").buttonGetIcon());