It is a lot better now but you should use more polygons for corners. I don't remember how it is made in BTB but I think it was panels. I used 5m for straights and 1 or less for corners. Select the part of the track you want to edit and edit this panel value.
The terrain has to be edited anchor by anchor, yes! You can move more than one at the same time, but in the end, you will have to move one by one
The terrain has to be edited anchor by anchor, yes! You can move more than one at the same time, but in the end, you will have to move one by one