Belt driven axis question
Axis should definitely be at proper position. Otherwise you will get at least 2 issues.


Carriage will be pulled up which will cause stresses on rollers or slides and it will stress your belt
The way the carriage will go will change but because carriage itself is fixed then it will change the speed


3D printing is a precise process. Both issues will have impact on printouts and all your printouts will have broken dimension in the axis in which carriage moves.

Have a look on the picture (it is big to show details)



fig A shows a situation where carriage is far from the axis

In such situation the distance between vertical line of black cross and pink circle is almost unnoticable so both - the force and the distance (so speed) change are very small.

fig B shows a situation where carriage is relatively close to the axis

Then both - the force and the distance change is noticable