Greetings, Orgmoders.
After some discussion with Yantar on IRC, I humbly submit the attached diff for your consideration.
It adds new hooks to org-info-js to allow the following: 1. inserting page-specific HTML into each OrgInfo header, and 2. calling a custom _javascript_ function to run after any page navigation button/link is clicked. I have used these hooks to implement Org-fleuron, a custom config with nice navigation buttons, a greeting balloon, and embedded theme/fonts. You can find out more about org-fleuron here:
https://davidotoole.info/fleuron.html?#org5dc18bc and the page was made with the setup.
I also corrected some of the English messages displayed by org-info-js.
I hope you will find this useful.
Please let me know if you have any questions or comments!
org-info-src.js.diff