It it says G33 not implemented you have in configuration.h
#define DISTORTION_CORRECTION 0
That value must be 1 to also get G33. G32 and G33 are separate things.
The bed deeper in middle is a typical configuration issue. If the ratio diagonal to horizontal radius is wrong the head goes down/up towards the center. Since you measure diagonal quite precise you take that as fixed and modify the horizontal radius when centered until it fits. That is one of the things the escher tool does. It knows dependencies and uses a least error solution to guess better calibration values from measured heights.