Negative regions are offset one region in the positive direction (depending on which coordinate is negative).
Negative X chunk coordinate will lead to offset by one region coordinate n the positive X direction.
Negative Z chunk coordinate will lead to offset by one region coordinate in the positive Z direction.
Also region 0,0 is according to the on screen info, 4 times larger than it actually is since it overlaps region 0,0 / -1,0 / 0,-1 and -1,-1