Hey Ed,
Welcome back to the forums and Happy Thursday 🙂
I recently helped another customer with a similar request. I’ll copy/paste my reply below. Please note that this type of customization extends beyond what we’re able to provide, but we’re always happy to point you in the right direction.
To get started changing the columns from 3 to 4, you’ll need to familiarize yourself with the Isotope Script as it’s what we use to create the layout.
Then we run a script to initialize Isotope on that page.
/events-calendar-pro/resources/tribe-events-photo-view.min.js
Non-minified Version:
/events-calendar-pro/resources/tribe-events-photo-view.js
So to change the formatting you can wp_dequeue_script the first script and then replace it with your own.
Best of luck with the customizations and thanks for choosing PRO!