How to add Tiled gameObjects to matter

I´m working on a top down racing game, and have been designing my levels in Tiled. I have an Object Layer with checkpoints that will be used to check if the player is going in the right direction and to navigate ai racers.

I´ve been able to import the map and add physics and collisons to the regular Tile Layers, and I have gotten the objects from Tiled in to an array using getObjectLayer(), but I can´t figure out what to do with them to make them them register collisions. I´ve tried looping through the array and adding them as gameObject to matter like this:

checkpoints.objects.forEach(checkpoint => {
        
        this.matter.add.gameObject(checkpoint);
    });

but I get an error message:

“Uncaught TypeError: i.gameObject.emit is not a function”

Could someone please tell me how to add gameObjects and have them collide the correct way?

I somewhat solved it by looping through the array of objects creating a matter rect for each using the objects specifications, and offseting the x y values by half the width/height.

The problem now is that the rects that are rotated gets placed slightly wrong, and no mattter what I try I can´t seem to get it right.

I´ve been trying to fix this seemingly easy problem for days now and would greatly appreciate some help!