I can see you have raised the belt from the floor level. When you do this you need to put a block under each anchor point locked to the floor to ensure it can not bend. Even small uneven bends from different directions as the belts pull tight have an effect on accuracy.
Also looking at the 198calib.yaml file I note you have all the Z values set to zero. This only applies if all the anchor points are at the same height as each arm. The only one I can clearly see looks like its raised.
By default, the Maslow software expects the height of each anchor point to be the same as the sled, and compensates in the maths with different heights specified in the maslow.yaml file.
Can you provide a photo of each of your anchor points and a shot showing how parallel the belts are when extended.
You could also try lowering the anchor points to floor level and resetting the maslow.yaml file with the default values as per Adjusting height of Anchors, When, Why and How
I just went back and read how you have spacers to raise the anchor points, so that is correct, so long as there is no movement when belts pull on it. May still be worth trying it with default values and without the spacers though.