I know I am not staff but I have a D+ plot and I must say minevast has tough graders. (which I think is smart) here are some tips.
1. Use tarrafarming there is a 99% chance that you will not get graded if you don't have a hill or mountain. when you get your plot you get it flat. plot's are often boring if you don't have some sort of hill.
2 fill up your plot. if you have a cool house in the middle of your plot but nothing around it they will not grade it.
3. Do not plant sapling trees. make your own trees. It gives more of a chance if you make your own trees.
1. Use tarrafarming there is a 99% chance that you will not get graded if you don't have a hill or mountain. when you get your plot you get it flat. plot's are often boring if you don't have some sort of hill.
2 fill up your plot. if you have a cool house in the middle of your plot but nothing around it they will not grade it.
3. Do not plant sapling trees. make your own trees. It gives more of a chance if you make your own trees.