Physics are quite o.k. here, but you have to include the conditions.
My replay with a top G20 iron and a Cally shows a short roll forward of 3 yds, but I didn't use any backspin.
A shot with half backspin will sneak back two yards, showing only little of the expected reaction.
Looking at your low level equipment I'm puzzled that yours didn't roll forward even more, because the Starter ball doesn't take much spin, nor do these Starter plus irons. But, trajectory is high on these clubs (like mine which only are bit longer), so it's enough to stick.
I also seem to remember that the slope is not as severe there as the description tells.