This is a simple idea that's long overdue. Currently when building alerts we have to go the summary page to view the objects that are affected by the trigger condition. If you build a bad trigger condition you have to go back and forth to validate if your alert is built correctly.
The idea is simple, show affected objects on the trigger condition page. See below for how it could look.
I didn't add it to my image but at the bottom of the screen where the <next> & <cancel> buttons are located maybe a new button can be added that says <validate> or something cooler, that validates or checks the trigger conditions for affected objects.

I believe having the ability to validate and see what objects are affected by the trigger condition, while building the trigger condition would make life so much better.