Regions and label, what about coordinates?

[Phil353556]

Hello,
This a follow up of #3950
with regions now added.

I used what you shared on #3950 . That's great.
And I added "regions" like (labels are months name : Janvier > January, Février -> February and so on)

I ran a few tests and as the number of values on the X axis increased, the label was no longer displayed in the correct region.
The issue I have is about the position of this label. Until 180 values (=6 months) that's ok, then the label is not at the right place. There is a shift on the right.
see screenshots:
OK :

Not Ok :

May you tell me more about coordinates x and y for label?
What I should in a perfect world, is to have the label displayed in the center of each region.

best regards / Phil