Lots of good answers already provided.
See if increasing the length of your top link will make your rake more aggressive. The tines should then pop up sticks and chunks rather than ride over the piles.
Suggest putting an angle on the rake to put the debris into wind rows as you rake.
I find it easier to make smaller piles that can be quickly picked up with the grapple and moved to the slash pile rather than trying to just rake in order to move the mulcher debris over an extended distance.
Not sure if you have rock...raking may pop some rocks out of the ground too.
Smaller debris can be cut up with a rotary cutter once you get the big chunks raked and moved. Give it a year of fairly frequent mowing and it will start to look more like a lawn than a battlefield.
This is one of the areas we had forestry mulched in Nov '20...with a slash pile still waiting to be burned. We saved the Maple and Cherry, but It had the stumps and tops from a dozen 2' to 3' DBH pines which I cut, lots of other 8 and 10 inch trees, loads of Autumn Olive and thorn trees everywhere.
I used my stump grinder on about 75 stumps of various sizes in this section, but that's for a future chapter in your journey.
18 months later, we call it "The Park".