Lectora creates %-score variables for each (graded) test and for each test section. Check the “Reserved” tab in the variable manager (Tools > Variables) to find them.
I’m using the results object regularly and it’s usually doing a good job.
When searching the community about the custom results page you should be aware that it only exists since (I believe) v16.1. The custom results page in versions before that was … impressive. I’ve spent hours to customize it with very interesting effects. The current object really is a massive improvement, even if your options to customize it are still restricted. But at least it’s an object on a normal page that can be edited normally. Trying to add a simple image to the old results page made Lectora freeze, crash, corrupt the whole title, slow down the computer and / or a combination of unique/custom effects, none of which was nice. Even when you did not try to customize it, it was unstable.
But again: The current results object is a good thing.