Lower your bucket to the finished height your trying to achieve, then track backwards with the machine
or
lower the blade to finished height, swivel the cab round by 90° so your looking directly down on the blade, then track forwards
or
buy or make a grading beam
Concrete posts and gravel boards can be a pain at the best of times.
Personally I'd do as the contractor said... bark and top soil to fill in the gaps.
If you start digging out to drop the gravel boards you could end up with a fence top that is out of line in-between bays.
Did your delightful neighbour share the cost?????🤩
We've got trade accounts at 3 builders merchants.
I do a bulk list of items required for each stage and present it to the B.M's and see who comes out cheapest.
The only items that stay constant is red building sand and the brand of cement so the muck is the same colour throughout the build.
You can use build warranty for any structural build issues with your property including garages.
NHBC will back peddle as fast as they can and deny all liability.
You may need to employ a structural surveyor, one that's also handles litigation cases.
You can also use your insurers if you have building cover.