Handle position on the window not centered - defect?

Visually, I think this is not a defect. If you live there, you won’t notice it anymore. You also get used to the operation very quickly if you open or close the windows often daily.

Ours are not centered either, if that comforts you. I wouldn't have noticed at all...

I wouldn’t worry about window handles for you at all. In new buildings with ventilation systems, I wouldn’t know why I should open windows anyway. Patio doors yes, regular windows – almost never. I have now installed some fixed-glass windows in my house. Narrow frame, no mullion, and thus lots of glass and view to the outside.

I have never seen windows that are different. The handles are actually never in the middle. That would also be ergonomically complete nonsense.

Then take a look at the tables. Of course, the windows of the OP have a lower handle position according to the table. Even in standard, they are rarely in the middle. In my opinion, the window manufacturer should have clarified that windows with a lower handle position are delivered. Because that is not standard.

What does the offer say about the handles and fittings?

Such simple questions then remain unanswered. o_O

As part of barrier-free construction, DIN 18040-2 Barrier-Free Construction - Planning Principles: Residences specifies in section 5.3.2 that window handles must be installed at a gripping height of 850 mm to 1,050 mm above the top edge of the finished floor (OFF).

Presumably, barrier-free construction is desired somewhere, and a level-access shower is probably also desired.